Nick 568,
I priced repainting/refinishing wheels as well. By the time you factor in the costs of stripping, prepping, and painting it's very expensive. Figure $200 or more per wheel. A new set of wheels can be had for only slightly more.
If you do decide to repaint, I would carefully investigate the company providing the service. Aluminum can be easily damaged during stripping process. The company should specialize in wheel repair and repainting. I would also ask for some referrals.
As for powdercoating, I find it tends to give a different appearance than paint. Depending on the process and materials used, it can be very durable. Once again, you have to be careful about stripping and prepping the wheels.
BTW, Nissan specifically warns against chroming of the stock wheels. I would personally not buy aftermarket 'chromed' versions of the factory wheels. Read this tech bulletin for more info:
http://www.nicoclub.com/FSM/Ro...c.pdf