I bought one for $500 about 5 months ago from walmart.. and I regret it so much..... It makes so much noise i can't hear my TV from 5 feet away. And I haven't even used it much.
My advice: If you want to buy one, dont buy cheap... you'll regret it after a couple of months. trust me. 
I now have this useless piece of crrap that i can't use.. and i can't even sell it.. waste of my hard earned $500 bucks.