For now, a Radeon 5770 is probably the highest you could go. However, if you just a few more days until Black Friday, I would guess there are going to be some pretty sick deals.
Here's the cheapest 5770 on newegg
what features are you looking for from the card? DX11? Multi monitor support? Crossfire/SLI capabilities? if you can give us a better idea of what you want from your card, we can give you better suggestions.
also, theres are you talking about price after MIR or before? If you're willing to take MIRs into consideration, you can get a much better card and still stay within your budget
I forgot if we are including the price after rebate or not. I think, once you factor in tax and shipping, if $120 is the absolute limit, then the 5770 is out of range. The cheapest 5770 on Newegg is the HIS 5770 for $140, but $110 after rebate. http://www.newegg.com/Product/Product.aspx?Item=N82E168...