does anyone have any benchmarks for these cards

Solution
Good website that reviews each card the same way, so you can really compare different chipsets against each other:

280x from Gigabyte: http://www.techpowerup.com/reviews/Gigabyte/R9_280X_OC/6.html
770 from Gigabyte: http://www.techpowerup.com/reviews/Gigabyte/GeForce_GTX_770_WindForce_OC/7.html
780 from Gigabyte: http://www.techpowerup.com/reviews/Gigabyte/GeForce_GTX_780_OC/6.html

and to add one more card within the general price range;

290 from MSI: http://www.techpowerup.com/reviews/MSI/R9_290X_Gaming/6.html