I would stay far away from Walmart bikes they will be more headaches than their worth and only make you angry! If all you can afford is $250 I would start looking at Craigslist for a nice condition used steel bike, you can find really nice high quality bikes that were very dependable in their day and still are today, and in a lot of cases those older bikes weren't even rode much so they'll be just broken in! You'll be able to tell by what condition it's in and how well the owner took care of it, make sure the ring gears are not pointed and short, and no strange ripples in the paint especially near lugs, ride it with no hands to make sure it tracks straight (be careful here because the crown of a road could make it go in one direction so try to find a flat road). Depending on how long they sat you may have to do a complete lube job to get them in perfect working order. By they way, make sure the bike fits before you buy it!