No where near, a 7970 would absolutely cream two 560's in SLI, and they would cream two 560ti's in SLI too. Roughly speaking a 7970 GHZ = 680.
I've never seen a 7970 for $900 in any country, what country are you from? You might be picking a dual GPU by mistake.
I live in Albania its actually around 650 euros but i converted it in USD Thanks for the help btw, i guess i'm gonna get the 7970
(its not dual btw)