Sure there is a vendor where you live... You are sitting there looking at it. However there is a problem
There are a lot of makes and models of air conditioners out there, Each and every one has it's own idea of what size filter to use. So I'd go to the maker's web site. Find out who their dealers are.. Odds are rather good that camping world is going to be one of them.
Then you go to the dealer's web site and order the product.. A few days later KNOCK KNOCK and a man in a brown uniform hands you a box, you sign, and your filters are inside.