upgraded handlebars? That's a first, never heard that before. Those walmart bikes are great for hanging in the garage and looking at, or maybe occasional riding around the block.
What city do you live in? My guess is you can find a used, rigid (ie no shock) mountain bike for less than that amount that will be sturdier, work better and last longer. Try Craigs list and feel free to post a link or two and we can help you sort through the muck. The good news is if you get sick of it, you can probably resell it for the exact same amount.