I bought a Novara Bonita hardtail WSD mountain bike at REI (previous year's model so got a clearance price). It's actually a pretty decent ride, and the components and suspension fork are adequate for gravel roads, fire roads, and easy trails. The only downside is it's as heavy as a tank (~32.5 lbs), which makes hills (and lifting it into the car) a bit of an ordeal, but at the lower price points (it retails for $569, but I paid $399), you just aren't going to get light weight. It's fine for a lot of rides, though, so long as you aren't trying to break any speed records. Our REI gives decent bike service and spent a lot of time going over the bike with me when I bought it, and it fits me very well. So yes, it can be done (less expensive mountain bike) so long as you aren't expecting it to be perfect in every way! There will be compromises - I'd rather have high weight but solid componentry than the alternative. And I definitely agree with the others who say do NOT buy a bike at Target, Wal-Mart, etc.

Good luck - let us know what you do!

Emily