I have a buddy that sanded his rims down and refinished using sealer and clear coat paint. I forget the steps that he took, but its an inexpensive method if you have the time to do the sanding down. Finding product to do the refinishing is dead easy.
Years ago, there was a product that was used to chemically remove the coating on the rims, but it was so hazardous, its no longer on the market.
For the more expensive route you can take them in and get it done professionally. but that is very spendy.
I'll ask him how much it cost to do the sanding/clearcoat
Diamond White Classic Aurora - Back on the Road
Galaxy Silver Grand Prix GTP CompG - Soon to be mothballed