Hi Suzy,
I have a Ba'ader Hyperion 13mm eyepiece which I picked up here on Ice Trade for a steal of around $120. Its a 68 degree EP and I love it to bits.
Slight curvature I would say using my F5 Dob, but really not that noticeable. Quality and fit/finish is beautiful, almost comparible to my Pentax XF 8.5mm. Its also extremely robust and solid. No fragile bits to break off. Its colour is also very warm to look through. Pleasant views that are easy on the eye. FOV and eye relief is quite good and immersive as well.
The real beauty of this eyepiece comes down to its versatility.... You can remove the front lens element, which is also the 1.25" EP barrel to create a 26mm 2" barrel EP!!! Thats TWO focal lengths in one! Awesome.
It also has T ring mounts on it as well as rubber eyecup and comes in a sexy leatherette type pouch.
New price on Andrews is $199 each and I would highly recommend this FL EP as I have one and its the first EP to go into the 8" or the 12" scopes.
Its a cracker and not too expensive. Save the extra cash for the next purchase....such as a cake or pressy for me for being so helpful
Worth a look!
Cheers
Chris