If you want dirt-cheap wireless system for your guitar/bass, here's a crazy suggestion:
1.) Take a crash course in DIY electrical engineering from the Internet & library
2.) Study microphones and wireless guitar systems. I noticed that the standard mics we use for our home karaoke system are similar to our instrument cables (both use mono 1/4" plugs)
3.) Get an Enzer wireless mic system. Mod it and maybe you might get a wireless guitar system.
You need screwdrivers, soldering iron and desoldering pump, solder, a mono output jack and a plastic casing for the transmitter.
haha, I might wanna try this out, but now I have no money. Feel free to try!