I would try a local bike shop instead of walmart. Almost anything from a real bike store will be better quality, and you will (hopefully) get better advice from store that wants to earn your business, as well as proper adjustment and set up, and service later on when you need it. If walmart has succeeded in obliterating every local business in your area, as they have done in most of America, and there is no bike shop I'd get on the phone with the folks at Nashbar. You will need someone who is mechanically handy to help you assemble a mail-order bike though. Also don't forget stores like REI also sell bikes, and are better than Walmart for advice and service.
You can also look for used bikes in your price range. A $200 used bike was probably a $500 new bike from a few years ago.