What is the best way for DIYer to buy HVAC equipment and supplies if EPA 608 certified but not contractor?
This is just an extension of Ed Beal's comments. I would defiantly set up an account with a vendor who has national outlets (maybe two) which usually allows you to purchase from any outlet. Unfortunately if a state has certain regulations that only allow certain vendors to purchase regulated products, there is not much anyone can do about it. 

You have an unusual situation, but if you needed anything immediately the only other option would be to overnight from you home supplier.