The best upgrade you could do for $200 or less would be getting a GTX 960 or R9 380, and I don't think either would be a big enough jump to warrant upgrading. For a little more money, you could get a R9 380X, which would maybe be a little more worthwhile. But I think you'd be better off saving up more until you can afford at least a GTX 970 or R9 390.