X2...
www.x2digitalwireless.com
I have the "stomp box" version. Make sure you get an AC adapter for the receiver, and a
rechargable 9v for the belt pack. I recommend the one I linked because it's "9.6v" which is above higher than most "9v" rechargables (they're usually in the 8v range), so it'll give you the juice you need and last for a few gigs.
It's very clear, LOUD (hotter than just a cable) and has solid range. You need to be line of sight or you may get some drops (I haven't had any yet), and at long distances you will get a delay.