Call me crazy - but I'm thinking about painting my aluminum 15x8 OEM "snowflake" wheels black. I know I can buy black steel wheels for around $48/ea, but I'm a cheap, cheap man. I doubt I could sell the snowflakes for enough to make up the price difference.

So - has anybody ever painted aluminum wheels? Any special prep needed beyond removing oxidation etc? I plan to paint them semi-gloss black. I know they won't have a s tough a finish as powder-coat - but then I can just hit any nicks with a spray can & be done with it.

Yes, paint won't stick to aluminum unless you prime it first with a special primer. I forget what the primer is called, but it bonds with the aluminum and sets base for paint. Normal primer nor paint will stick to aluminum and will flake off over a period of time.
Go to an auto paint shop and they should be able to tell you what the name of that stuff is... BTW, you said you were cheap.. that primer is rather expense... somewhere around $30/quart if I remember correctly... Ran across all this when I was painting an aluminum boat for a friend...

Yep I painted mine. Clear coat was flaking off and they were oxidizing so I figured what the hell they're already ugly.

So here's what I did:

1) Used paint stripper to remove all the clear coat.
2) Then I bead blasted them here at work (kinda like sandblasting).
3) Then I used Rustoleum gray primer.
4) Then top coated them with Rusteolum Hammertone Black.
5) Finally finished them off with clear coat.

This was 3 years ago and they are still holding up. No flaking at all. The only dings I have are from letting the lug wrench slip when I was rotating tires.