Welcome to TE. Might want to surf over to the Getting to know you thread and post a quick introduction:
http://forums.teamestrogen.com/showthread.php?t=2001
I've got to be honest it will be hard to find a low cost MTB because in my view the words "cheap" and "full suspension" should not be used in the same sentence. If you're doing the kind of riding that calls for suspension that will cost. Hard tail, your classic no frills, no suspension MTB can be cheap and super fun. There are some good affordable gravel bikes out there. It really depends on the kind of riding you want to do and where and how. We're really need more time and information to give you ideas.