The car probably needs new ball joints. Ball joints are things that do wear out. They are not hard to do, and threre are plenty of videos on youtube that show how to do it. You can even rent the tools from an auto parts store and it will still probably be cheaper then having a shop do it. As for wal mart, thay are not a mechanic shop they are a box store. I would try and find a local shop with just a few guys that you can build a relationship with and trust that they are doing what needs to be done.