Several things to consider when powder coating your wheels:
1. You must dismount the tires and remove the center caps and valve stems. Only the metal is able to be powder coated, not plastic or rubber. You would then have to re-mount the tires with new valve stems and this can be rather expensive unless you or someone you know can do it cheap.
2. Next, you would have to either leave the center caps how they are or try to find a paint that would match the powder coat and paint them separately (or you could leave the center caps off).
3. Powder coating costs more than painting, materials and labor included.
4. The powder coat is more durable than paint, but it can still chip or scratch if you happen to hit some debris or get too close to a curb. You can touch up powder coated wheels with paint, but it doesn't always match. If you painted the wheels, you can touch them up with the same color (minus any fading from the sun), or re-do an entire wheel much easier than if you were to powder coat it again.
5. It is argued that the powdercoating process weakens the structure of the wheels.
...can you tell what side of the fence I'm on?