I've been seeing a fair amount of people looking for budget gaming GPUs in the forums lately so I thought I'd throw this up. Newegg has MSI's 7770 for $80 after MIR until 7/22. You could also get this Powercolor 7770 for the same price until 7/17.
The 7770 is not the most potent gaming GPU, but it will give you 40+fps at 1080p and medium-high quality settings on almost every game available today (besides Crysis 3). If I had a little more than $100 I'd still go for a 7790 which I've seen on sale for ~$110-120 (~40% increase in performance for ~40% higher price), but a 7770 for $80 is a guilt-free purchase if you're exploring PC gaming or on a tight budget.