How many spinners do you want anodized? Is it clear anodize or color?
There is a company here in town that manufactures marine components. They have one building strictly for anodizing, since most of their products are aluminum. Years back, when I had my manufacturing company, they were a customer of mine. I might poke around and see if anybody I knew is still there. Maybe your spinner could take a free ride...
No promises, but give me a few days.