I do not recommend a used video card, Your asking for trouble unless it comes with the original receipt and has been timely registered. Thereby maintaining decent warranty. And all to often there is something wrong with them. For a few dollars more you can get a new one on Newegg.
Also you may want to go with low profile Memory so not to have a problrm with you cpu cooler
May I ask what your expectations of the graphics is? A playable ultra playthrough or medium-high?
Because if you want ultra on the most demanding games right now, like watch dogs, then the r9 280x and higher or geforce gtx 770 and higher is the way to go. This means higher prices but it is the road.
But if medium-high stills appeals to you then geforce gtx 660 or r9 270 should do the trick (im not entierly sure, so help me out here). This brings the price down. Its all up to you, but otherwise a good build for the money. Though you could upgrade to an amd 8320 or if you flip the coin and go intel then the i5 4670k or 3570k is a good choice for a decent coin!