Mothers direct will rape your billfold, the last I noticed. The Mothers Aluminum polish is available in most Walmart stores (in the smaller containers) I have a couple outlets in my area that I can get the larger containers that last a lot longer. However the 4 ounce "Billet" polish
http://www.mothers.com/02_products/05106.html is availible from many supplliers that handle custom wheels and of course on the internet. I purchase mine at a truck supply store in Wichita, Kansas.