GPU for a EVGA Z68 FTW. Help please

Got myself a EVGA Z68 FTW  P/N: 160-SB-E689-KR. 

I'm planing to build a gaming PC around this board. Now im debating what to do for the GPU. One, two or tree GPUs? I'm hoping to do this in the next one or two months. I'm expecting to have a budget of about $400 ($500 if im lucky).

I would apreaciate any help. 

you will never find a good two three gpu configuration in the price range 400-500$. And it is always better with a one card sulotion, less parts that doesn't work :).

Is the budget for the whole rig or just the graphic cards? 

Less parts = less headaches, i agree with that. The budget is for the GPU alone. 

Thanks for the input tho.