Almost all atomotive stores carry it, certainly the Ford dealership there should have it, and finally a lot of places like Midas, Goodyear....etc...carry it for their customers [and will put it in for you]. That's how it is here in Colorado--imagine it's the same there.
Look for HC134a at an auto parts store. It comes in 16 oz cans, and they sell kits with the hose and adapter to install it yourself.