Well I tried a Line 6 for about a month and it sounded great. Then one day it started dropping out, so I returned it and bought a great EV lead mic.
If I were to buy one again I would get a Sure in the $500-$600 range.
Samson Technologies has some great products as well. Great professional products at very reasonable prices. I currently have the Airline Synth Guitar wireless system and its really, really nice. Truly wireless ... no belt pack. Low S/N ratio -- plenty of transmitting power -- and very true audio (i can't tell the difference between the wireless and the line).
They have a complete line of microphone products from studio, to digital, to wireless -- you name it! You can check them out at http://www.samsontech.com
They don't deal with a lot of national outlets ... (Guitar Center, Musician's Friend, etc) but it's not that hard to find a dealer. In fact, my "guitar guy" here in El Paso became one of there dealers because of me!
God Bless You!