I got a bunch of these things off Amazon for dirt cheap in all 3 sizes for our cars. They seem made well enough.
My question about your question is, you can anodize plastic?
You could buy then paint them. If you really want a shiny metal look you can paint yours with Dupli-color Metalcast, but I don't know how long that would hold up before it started to chip.
http://www.bing.com/images/search?q=...st&FORM=HDRSC2