Recommendations for Upgrading GPU

Hey guys,

I live in Australia and everything is overpriced.

I currently have a Sapphire 6870 1GB GPU and while it does the job, I want something to be able to play some of the newer games out there like Watchdogs and such. I was thinking of buying a 280X but not sure what model. They range from $320 - $400.
I was looking online and found a Gigabyte OC 280X that has been used for 2 months and is only $200. I suspect that it has been used for mining, plus in the picture there was about ten of them. The seller is also selling a 750w PSU which makes me think that he has been using these for mining.

Wait a week or 2 and see if the r9 280s go on fire sale and if not a r9 285 is good since it has support for all the new software goodies.

Even if it was used for mining, if it still has the warranty, i see no problem in buying used card, because in 9/10 cases it will have much better price/performance ratio than any new card. That way i bought my second GTX660 for about half the price.

But ask about warranty, here in slovakia (central europe) it is that as long as you have some document of purchase, you are good to go, even if it werent you who originaly bought that item from retailer.