[janoskiss (Steve H)]

I'll interpret your willingness to spend a "bit extra" as you want bang for buck good quality EPs: not super cheap but not very expensive ultra-wide ultra-everything big brands either.

Here is what I'd recommend as the general game plan:

1) Low-power widefield / finder EP
It sounds like you're happy enough with the 28mm Orion EP, so let's start with that as your widest field / high-power eyepiece.

2) Deep Sky workhorse, Lunar, low power planetary
The next one to look at is a deep sky "workhorse" EP and mid-low power planetary. The former implies something with roughly around 2mm exit pupil, which for your scope is achieved with an approx 9.5mm, or let's say 10mm EP.

If you were going for an ultra wide (80-deg FOV or more), a 9mm would be ideal there. But on a sensibly restricted budget it would be better to go for somewhat less FOV (more in the 60-70 degree range) but with better optics than the same money would buy you in an ultra-wide. That means, e.g., 12mm 60-degree, 11mm 65-degree, or a 10mm 70-degree EP. All these also very nicely frame the Moon which will fill most of the FOV.

The 10mm/70-deg combo would be an excellent choice if you can find a good one. Pretty close to ideal for the human eye to tease out the most detail on fainter deep sky objects and still a big immersive 70-deg FOV.

Unfortunately the only EP I can unreservedly recommend there is the Pentax XW-10, which is ridiculously expensive (especially since the AU$ took such a dive; it is also a ridiculously good EP though).

But there are less expensive alternatives around that offer good performance. The Baader Hyperion 10mm is one I know of (you can easily find it for under $AU200). It also has provisions for camera attachments and some other tricks you can play with its "modular" design. Both the XW and the Hyperion are big heavy EPs, if that matters to you (it does to me; I prefer pocket-friendly lightweight EPs).

Another excellent choice here is the Pentax XF 12mm 60-deg. This is optically superior (in terms of contrast, sharpness and transmission) to just about any other similar TFOV widefield except the XW 10mm (and by all reports the Nikon NAV SW 10mm, but those are even pricier than the XWs) --- in all respect but one that is: it's only slight issue in a scope like yours is slight field curvature visible near the edge of the FOV. Your eyes might be able to accommodate it though (you've got to try for yourself to see).

But there are lots of and continually improving EPs coming out of China (and some from elsewhere) that I have not kept up with recently. So there are no doubt other options you might like to consider. (Same comments apply below.)

3) Higher power DSO, mid-power planetary/lunar
You'll want something with roughly 40-50% more magnification here than #2 (if AFOVs are about the the same). There is a clear winner here for me: the Pentax XF 8.5mm. It's optically as close to perfect as they come: superb on everything from DSOs to planets, and performs flawlessly at any f-ratio. Unlike the 12mm XF it has no field curvature issues at all. It's optically up there with the XW-10 or XW-7, with just 10-degrees less FOV, much less bulk and weight, at 1/3 to 1/2 the cost. If you shop around you can still find these for not much over $AU200 (or equivalent in $US or JPY).

But if you're not happy with "only" a 60-degree FOV, you might look for a 7mm widefield. Can't recommend any bang-for-buck ones off the top of my head. I used to use the XW-7, and don't know of any less expensive ones directly comparable. If you get the 10mm Hyperion, it possibly can be fiddled with to turn it into a 7mm (with the modular design spacer rings and what not), but you don't want to have to disassemble and reassemble your EP every time you want to change focal lengths. Maybe two Hyperions could work here.

Note about the Hyperions and their "modular design" feature (that lets you change the focal length): when you reduce the focal length from the default, the edge-of-field performance tends to degrade, especially in faster scopes. Conversely, when you increase the focal length the edge of field performance tends to improve.

4) Higher power eyepieces mostly but not exclusively for planets
Here I'd recommend several more tightly spaced focal lengths so you can select the magnification to best suit the seeing conditions:
6mm, 5mm, 4mm planetary EPs. I used to own some TMB planatery EPs around these FLs and they were quite good performance for low-cost, wide field (60-ish-degree), comfortable eye relief EPs. Fairly nice and light too. There are apparently similar EPs around from other manufacturers (also some TMB clones) these days, but I cannot vouch for them. If they perform anything like the original TMBs, they'd be well worth looking into, even in longer focal lengths.

That should about cover it. (And just in case you're wondering, no you don't really need anything between 28 and 10-12mm. But if you were to insist, 19mm Panoptic is nice. Second hand, the cost should be very reasonable.)

On Barlows
I have not mentioned barlows because some people are afraid of or just plain don't like barlows. I am not one of them.

Barlows do several things for you that individual focal length EPs cannot. For one thing, you can fine tune the magnification by adjusting the EP-to-barlow-lens using a simple extension tube. (In fact that's exactly how the Hyperion modular design variable FL works.) Secondly, good barlows combined with high quality simpler design EPs can give you exceptionally good high-power views of both planets and DSOs without giving up the comfort of longer eye-relief; e.g., A 12mm ortho in a good barlow makes for an excellent planetary EP.

Unfortunately the barlow I would recommend is no longer in production (AFAIK). I have not found anything else to be as good in 10 years (inlcuding televues, powermates, ultima shorty plus, you name it). It was the Japanese Orion Ultrascopic 1.25" fully-baffled 2x long Barlow (was sold under other brands too). There was also a 2" version, which used to be the University Optics' 2" barlow, that they've since replaced with a GSO I believe. (The whole UO range took a turned to poopoo some years back.) These barlows control reflections and light scatter like no others and yield very high contrast. They also eliminate abberations of most eyepieces (even cheap and nasty ones) - almost like magic. But I believe that is a simple consequence of the fact that they are longer than most other barlows. If you can find one second hand, jump on it.

On Geese and Ganders and my personal favourites
Eyepiece selection is a very personal thing and even ones own preferences shift over time. Here is my current collection that I am very happy with and use it in the same type of scope you have:

* 30 mm Ultra-Wide (fairly inexpensive big Chinese piece from Andrews) - this is not great on its own in this fast scope. Lots of edge of field abberations. I rarely use it that way. However in the 2" UO Barlow it becomes an excellent 13-14mm ultra-wide that is abberation-free sharp edge-to-edge. Even on the Moon it's perfect. Much preferred to my old Nagler T6 13mm. Just to be clear: I don't recommend this EP. When I bought it years ago, it was a bargain on special for <$70. Now it's closer to $200 and it's not worth it.

* 35 mm Orion Ultrascopic: this is an unnecessary luxury item, not really needed, nor exactly well suited to an f4.7 because it yields 7+mm exit pupil, but it's probably the world's widest TFOV 1.25" EP.

But here are the ones that get used most, and 99+% of the time I'd be happy with only using these:

* 25mm Antares Elite: my default low-power/finder eyepiece. (The Antares Elites are no longer made, but Parks Gold Series is still around and it's practically the same.)

* 15mm Antares Elite: low-mid power DSO EP; frames the full disk of Moon nicely with loads of detail to impress your non-astro friends.

* 8.5mm Pentax XF: mid power DSO and low-mid power planetary/lunar. This is the ticket! If you find one for under $AU200, don't even think about it. Just get one. Or two.

* 1.25" Orion Ultrascopic 2x barlow: combined with the above for higher powers. (Using extension tube to get to any desired magnification.)

So just the latter three EPs (the two Antares and the XF) combined with the Ultrascopic barlow make a very good comprehensive set. They are not particularly wide FOV EPs (52-degrees for the Elites, 60-degrees for the XF), but they are optically excellent, brilliant performers in the fast scope and very comfortable to use, compact and light. These factors are much more important to me than more FOV mostly in my peripheral vision. (And I've gone through many widefields, LVWs, Panoptics, Naglers T4/T5/T6, Pentax XWs etc etc in the past 12 or so years.) But that's just my personal preference. Others have different preferences and that's fair enough.