Repainting a bicycle that already has nice paint on it?

I am thinking about buying this cruiser that already has a nice paint job on it as if it was new but I don't like the color so I am thinking about repainting it, powder coating it, airbrushing or something...whatever's cheapest. Do I have to remove the paint that's on it? How much would it cost to repainting/powder coat/airbrush it if I don't want to do it myself? Thanks :)