If you have access to one at your gym, you could have a the cheap one at home and use the gym one to make weight.
I used to use a cheap one, but I woke up at "222" without clothes sweated my ass off to drop 3 pounds and then ended up weighing in at 215 with boots and clothes. I was pissed. Worse it could go the other way and you could come in heavy and not make weight at all. So no, for competition purposes I wouldn't rely on an a cheap one.