I've got 2 Scorpion3 (GunCon2 compatible) light guns that I used on my cab for a while. They worked fine when I pulled them out. I built a dual power adapter for them that I'll include (just attach it to a PSU power + ground). These would probably work great with the AimTrak too (haven't measured, but most guns seem to work with some modification).
I'd like to get something out of them. I have ~$60 total into them, so if someone wants them for $25 I'd be happy. Local pickup is best obviously, but I can ship if needed.