Avaword,
I think a couple of the above threads could be mis-read, if you have spoked wheels, then really the best answer is to 2 pack paint them,but find a good sprayer as it's a fiddley job to get right, however if you have cast wheels, then powder coating is an option.
If you want the number of a guy I have used several times for cast wheel renovation give me a call. (just to contradict the above, he does a lot of classic car wire wheels which he powder coats with very good results. last time I used him, he charged me £26 per wheel, for blasting and then powder, which I thought a bargain, and they still look perfect.
Another option is to have the rims anodised and stainless steel spokes, but that gets expensive.
Andrew