There is not one answer and you'll have to decide.
Before I start I just want to say that most of the deal links are from my site, just you to know.
1. Lenovo Y570 with an I5-2430M and GT 555M - I know the I5 is a little slow, but you do get good laptop (build quality and so on) with an above-the-average screen. 700$
and you can also take the I7-2670QM version they sell now for 750$
review - from notebookcheck.
2. probably better, performance-wise, is to take the HP *some edition* for 650$ with Radeon 7690M, 8GB DDR3 and 750GB HDD and I5
- and you have the FullHD option OR you can just buy a 100$ SSD and make your laptop much more funkier.
reviews for the dv6t quad edition on LaptopMag were good.
3. 850$ for GT 650M and I7-3610M, 8GB DDR3 memory and 750GB HDD
(and all the rest)
You got the FullHD option also, for 150$.
4. The Clevo based Sager on XoticPC (that's the cheapest I've found) - GT 650M, Intel I5, 8GB DDR3 and FullHD display for 900$ (~872$ cash).
It should be pretty good especially because of the screen although I don't know if they put there their good screen (which is great).
As far as I've searched, I didn't find better deals. You CAN find more deals in the range of 700$-1000$ with GT 640M / GT 555M / HD 7690M and I5 or I7 but niether seem to be better.
About the GT 650M - remember it's at least 20-30% faster than the GT 555M