You can get a cheap veiled from FLChameleons. However I am partial to my peeps over at KammoflageKreations! Lol, not the cheapest though. But ya, veiled would probably be your best bet as far as a cheap cham. Just make sure the cage he/she is put into is not the bare minimum. Chameleons require specific things and some of them (collectively) are NOT cheap.
Remember that you get what you pay for. You should really do some research and use the site sponsors to look for a cham...it's better to spend some more money then get a "cheap" cham and end up having something unhealthy and spend the money on care that you could've avoided.