Personally I grab one with a good warrenty, heatsink, price, and from a reputable company. Than just overclock it. As overclocking a GPU is easy so no point in paying absurd amount of money to have someone else do it for you. Heck if your lazy get the specs of the highest OC card of that type and use those as the setting for whatever card you buy and OC it to that and stress test it at that just to insure it's perfectly stable. Though from what I've seen companies do small mild OC's to insure a high yield on cards for overclocking.