Ben
Quality eyepieces are a great investment in the enjoyment of your scope.
I am a big Televue fan. Others have their preferred EPs but I have found that the TV ones have satisfied me.
My fav budget EP is the Televue 24mm Panoptic (see
http://www.bintel.com.au/Eyepieces-a...oductview.aspx ) but it is reasonably pricey and may be a bit close to the 28mm you already have.
Next one may be a 13mm Nagler (see
http://www.bintel.com.au/Eyepieces-a...oductview.aspx ) In your scope using this EP along with the 28, you would get powers of 36x and 77x. I have owned this EP and it is a cracker for the money.
Unless you are going for plabets and small PNs that will do almost all your observing.
Malcolm