Currently have that exact same card, and I am upgrading as well. I recently bought an R9 290 off ebay for more than $100 less than what it normally sells for (the guy had over 450 great reviews, a money back guarantee, and the card was brand new). Obviously that was sort of a unique deal, though.
I kinda agree with the other guys. Perhaps you should wait for newer cards and stick with what you've got for now. It all depends on your budget and goal resolution though.