Beware: A bargain is not always bargain.

Recently a private school in Adelaide purchased from EBAY a bunch or brand new radio mics for use on their musical production. They were very happy with their brand new radio mics until they started to fail during thier major musical. The audience complained, the school was not happy and tried to blame the theatre technician. The problem was they were a cheap brand with a bad reputation and they did not understand what they really needed. They thought they were buying quality at a cheap price and got stung.
The moral of the story is buy a reputable brand or if you cannot afford new, hire from a quality company quality equipment.