Hello good people!
I have an option of buying a used EVGA 015-P3-1582-AR GeForce GTX 580 (SC Superlocked) 1536MB GDDR5 for $230 or a new MSI Radeon HD 7950 OC 3GB for $290.
Both cards come with warranty.
I know the money difference is not huge, but I am a student, so proportions are shifted :P
Once overclocked to its max, the 7950 will practically be twice as strong as the 580. $60 is easily worth it!