Get your googling going for local metal finishers, a chroming place, powder coaters, they will all do ally polishing, or at least point you to somone local who will..
I did these old Saint cranks in a fit of boredom, haven't got quite the good finish like on the ones above but these are only hand polished, if I bought a buffer I am sure I could get them a lot better.
I did it with Kleen-off oven cleaner, you are looking for it to contain Sodium Hydroxide.
Basically took a little while, stuck cranks in bucket, sprayed with oven cleaner and left for 15-20 mins and then scrubbed the loose anodising off with a green pan scrubber and repeated about 6-8 times until all the anodising was removed. Gave it a quick buff with Brasso. I think if you use Autosol and a buffer you could get it to a better finish. I did try it with fine wet and dry but found it too much like hard work and the oven cleaner worked better without scratching.