Have you checked first to see what online upgrade offers they have now? I'd be shocked if you couldn't find an Optimus, mytouch or HTC One S for ~$100.
If you could spend another $50, Walmart has the Galaxy S for $149 w/ a $50 gift card. Much better specs.
I have had a series of crappy phones and I'm looking to upgrade to a smartphone. I have a budget of around $100. If there is something amazing for a little more then I would like to hear about it though. The only ones I'm seeing so far in my price range are the Concord, Prism and possibly the Dart. Which one is the best and are there any better phones in my price range? Any help would be appreciated!