True, more is better, but I can't find 270s at $40 around here (DFW). I regularly get decent stuff like 660s for $90 though. I really like the 750ti, but haven't seen many people letting them go yet.
My favorite cheap system I've built lately was a used i7-920, 6GB DDR3-1600, 1TB HDD, and a 7790 2GB. I picked it up used for $120 because someone crashed it and thought it was bad hardware. It even had a 750W Corsair PSU. I threw in a 128GB SSD I had left over, slapped a CM 212+ Evo on it, and it's now running cold at 3.8Ghz and chewing up games at 1080P nicely. I even talked the guy into saving up for a 970 OC Edition (I get to use it for a day or two first so I can see if I want to dump my 770 SLI setup.).








.
