Need help on finding mountain bike in my price range?

Fist of all I'm not experienced at mountain biking, I had the idea of mountain biking for exercise but after doing a lot of research on it I've completely fell in love with it and I know it's going to be a great hobby of mine. The type of mountain biking I'm going to be doing is dirt jumping/freeride/downhill and maybe as I get better some intermediate terrains. Again I'm just starting so that means I will possibly be falling a lot, I was going to buy a mongoose from wal-mart but after doing some research it seemed like all the experienced people say it's a horrible idea. I know that with my budget I can't really do much and I'm not expecting the best bike ever. What I'm asking for is some information, advice or anything really. On how or what is the best possible mountain bike I can get for no more than $200? Thank you! I will vote for best answer.