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Are you looking for a 1.25" or 2" eyepiece?
There is a Tele Vue 41mm Panoptic in eyepiece classifieds at the moment with the tag "Make me an offer!".
This eyepiece has the maximum field stop diameter possible (46mm) in a 2" barrel giving you the widest true field of 1.1 deg. in a C9.25 and an apparent field of 68 degrees that is just about right without having to pan around.
You can also get a brand new Tele Vue 55mm Plossl for $299.00 at the moment which has the same field stop diameter but only 50 deg apparent field. This is the 'standard' eyepiece for maximum true field and also maximum exit pupil of 5.5mm, (4.1mm for the 41 Pan) at f10.
If you have only a 1.25" visual back then the eyepiece of choice is the Tele Vue 24mm Panoptic. This eyepiece has the maximum possible field stop (27mm) in a 1.25" barrel and will therefore give you a maximum true field of 0.66 deg with the C9.25. You also get the 68 deg apparent field that is easy on the eye. The 24mm Panoptic is currently $379.00 new locally. It is more than your $300 limit so you would have to decide if it is what you want to spend.
The 24 Pan is one of the most versatile eyepieces around and performs exceptionally in just about any telescope and also only uses 1.25" filters for lower cost (especially with narrowband filters). An alternative to the 24mm Panoptic is the Tele Vue 32mm Plossl which will give you the same maximum true field but only 50 deg. apparent field. These are $175.00 new locally.
If you have a 0.63 reducer/corrector you can use that in combination with the 24mm Pan or 32mm Plossl. Note you cannot combine the 0.63 reducer/corrector with a 2" diagonal and 41mm Pan as you will not get focus.
A note on the 41mm Panoptic. Due to the design of the eyepiece having an upper body that is flat on the bottom can cause some inconvenience when tightening the lock screw if the lock screw is small as is the case on some star diagonals. A diagonal with a larger lock screw with longer shaft resolves this issue. Another issue is weight as the eyepiece can cause the visual back to rotate due to the weight of the eyepiece so ensure the visual back is locked tightly. A third potential issue is that the eyepiece body may foul the focus knob of the SCT. A longer visual back or shorter focus knob solves this problem.
Note there are many variations to the SCT visual back configuration and some variations cause no issues whatsoever. I had all the issues above and solved them with a WO SCT-2" visual back and WO 2" diagonal, both of which have nice long and large lock screws. The weight issue depends a bit on ambient conditions and how well the threads bind on the night. I also try to keep the eyepiece in a vertical position no matter where the telescope is pointing to avoid rotation due to weight.
A final though is you could also consider the 35mm Panoptic which is $469.00 new but does at times come up for sale used as people move to the 31mm Nagler. This eyepiece is 2/3 the weight of the 41mm Panoptic and is a superb performer in an SCT.
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