The big name tint manufacturers will only sell directly to tint shops or through select few distributors that only sell to tint shops, and highly discourage resellers. I know Llumar will blacklist you if they find out you're reselling their film.
Home Depot sells a brand called Gila that's actually manufactured by Llumar's parent company, Eastman Chemical, but I wouldn't recommend it. It's thin, hard to work with, and the last time I was forced to install some, all 3 of the 15' rolls had bad creases every 12 inches throughout the entire roll.
