IMHO there is no way to save money when you want good sound.
I don't know of any wireless mics that are really worth it for under $100.
You need a transceiver, a transponder, and a good lav mic. All of those things add up.
You would be better served by going with a mic with a cord... and even then, less than $100 is not going to get you anything very good.
Save up for something that is good!
