You are open to most guns then. The original Namco's (Guncon) are sweet, but very expensive. The Topgun II guns from playasia are also good. Most of the guys on here use them but usually this is because of the fact the work with LCD, as a lot of guns don't. However, they are very good!
You might want to wait a bit and check out the sonic gun system which is due to come out at the end of the year.