I'm not sure of the cost to ship it, but photographer's formulary sells a residual hypo test. Here's a link:
If someone here is doing some shopping at the formulary you could have them buy you a bottle and then ship it, might be cheaper that way. Just trying to help out! Also, you might try Robert White, they seem to be very helpful chaps and may be able to sort things out for you and come up with some residual hypo tester.