I'd seriously keep my eye pealed on pcpartpicker for a card in the 100 dollar range its really hard to find a card worth recommending at that range. I would say if you can spend the extra 20 or so dollars on a 650Ti. It is a better card then the 7770 however if you are pushed for cash then a 7770 will just just as well just the same.
Here is a link it is sorted by cheapest to most expensive as prices change this will also change
This is a great resource as it draws from the top retailers who supply each graphic card.http://pcpartpicker.com/parts/video-card/#c=115,118,79&sort=a5