It's hard to say what you should get since I don't know what you can choose from where you are. That's a dual core CPU w/hyperthreading so it's not bad. Your power supply will have an impact on what you can use. For low budget you will get more for your money buying used. An AMD HD 7850/7870 or Nvidia GTX 750, whichever is less expensive. For reference, a 250X is an HD 7770, which is slower than a 270 which is an HD 7850. If you are willing to game at 720p resolution you can get a less expensive card.
This all depends on the games you want to play of course. A card like a 250X can only do so much.