Oven cleaner supposedly works well to strip aluminum...takes anodizing off too... but any paint-stripper should do the job.
There is a powdercoating shop just off Allen Blvd. in Farmingdale that will sandblast them for you, they stripped and coated the centers of my wheels for about $85 each (multi-piece wheels)
It's Action Powder Coating
(631) 845-1949
105 Verdi St, #A, Farmingdale, NY
There is also reNu, I have no experience with them, just got their card yesterday... saw some samples that looked good.
www.renupowdercoating.com 105 Alder st. W. Babylon 631-249-7368
and Rainbow Powder Coating I've dealt with them in the past.
(631) 586-4019
49 E Industry Ct, #B, Deer Park, NY
and there is another powdercoat shop in Deer Park -