I too follow the pattern. My 15 inch rims would have left a bit too much space around a 15 inch pizza pan. I would have liked to have found 15.5 inch pans, but I only found 16 inch. I may actually go and trim the edge down if I get access to a proper cutting/lip-making device(s).
I bought them at a store called Ace Mart. It does mostly commercial kitchen/restaurant stuff, but it has a GREAT selection of all kinds of cookware. I paid about 6 bucks each for my aluminum ones.
Their website is here:
http://www.acemart.com/
Edit: It seems that they don't have any stores in your area, so if you ordered from them, the shipping might cost more than buying locally. Maybe you can find a better deal online elsewhere