Trying to buy "Termidor"? You can't, but only because the manufacturer won't sell it to you. You can, however, buy the active ingredient. It's legal to buy and own, and it's available all over the Web. Termidor, as applied, is simply 0.06% fipronil with no other active ingredients.
Do a Google search on "fipronil" and you'll find a bunch of fipronil-containing products for sale. The best, IMHO, is the Frontline flea stuff for dogs and cats. It's available as a spray-on liquid (so you don't have to open up a gazillion of those little single-use applicators), which you simply dilute down to 0.06% for termite use. (Don't get Frontline Plus -- it has an additional flea-specific ingredient added.)