I'm in AUS, so Toms usual GPU list often doesn't apply here as prices, apart from being more expensive, are varied.
I was initially looking at a GTX 760 for $320 (Gigabyte with the 3 fans) as this was in my price range, but a great deal on an XFX Double Dissipation 280x came up for $320, so I had to take it. It's now back up to $370.
Tom's put out their April GPU list, and the GTX 770 is the best bang for buck in that price range, unfortunately the cheapest 770 is $370 here. Over $400 if you want anything nice.
For a 280x, the XFX Double Dissipation is great. It's the usual XFX quality, and cooling on the new DD's works really well, and it's really quiet.
As the owner of an older system (slow CPU), and not planning to upgrade for awhile, AMD's 'mantle' API aims to take CPU load off the system during gaming. It's only just starting, but more and more games are coming out with it. Again, this won't make a difference with a new cpu, but my Q6600 is 7 years old, and I don't game enough to warrant a new system.