If you want to think outside the box, literally, I could recommend the RAAL SR-1b earspeakers (nearfield ear monitors) with the Ti-1b transformer interface box. You would need a headphone amp with a 4-pin XLR output that delivers a minimum of 2 wpc into either 16 or 32 ohms, so a pretty powerful headphone amp. But there is nothing like the SR-1b in terms of spaciousness, speed, detail, and transparency with the RAAL ribbon drivers, and they should fit with your hearing aids since they have a pad that goes behind the ears. Maybe not. And the system should be within your budget. The only downside is bass quality instead of quantity so some folks who like gobs of fat bass probably won't like the SR-1b. Check out the RAAL Requisite website for more details.
http://www.raalrequisite.com