A 50mm is 50mm on any camera... If you mean "will give me the same field of view as a 50mm lens would on a full frame" then you need to be looking at a 30mm lens.that is around 50mm when on a 1.6x camera.
What do you think is the sharpest lens availible at the moment that is around 50mm when on a 1.6x camera. For £500 or less new.
canon ef fit
He's quoted a budget of £500Depends on your budget too.