Out of those suggestions i would have to agree with Jamies idea of the never dull product if your going to do it on a budget.
I run a small custom polishing business, i am doing all the alloy on my mc21 as its going to be used as a show/promo bike.
Cgallant: The idea with the dremel is good, i have one of these but if you dont own one costs can creep up if your trying to do it cheap.
If you wanted to polish on a tight budget i would say use wet and dry sandpaper. Start with the oven cleaner to strip the oxidation off the part, then a low grade like 240 and work your way up to 800-1000 then use the never dull and some elbow grease to get a good finish.