or you could get 8gb ram like the ADATA 8GB (2 x 4GB) 240-Pin DDR3 SDRAM DDR3 1333 for $40 and be just a few dollars over budget (using newegg prices) or shop someplace cheaper like if you have a microcenter near you.
Either way the 2500k beats all those AMD's and thats before you overclock the daylights out of it. Its REAL easy to hit 4Ghz even with the stock cooler.
Your only problem is IF bulldozer outperfoms SandyBridge. I'm betting it won't.