i've bought them at swap meets and flee markets this guy had some for sale too: http://www.jalopyjournal.com/forum/showthread.php?t=177688&highlight=blankets
WWW.Elpasorug.com has a decent assortment. Type mexican blanket in your search, there are allot of websites. If you have a stuckeys or a large truckstop near by, you might try them as well.