Go to www.partsvoice.com You will have to register for the site and it's free. It is a resource that allows you to look into participating dealership's inventories. Make sure you have the p/n for the calipers. You may be able to find a dealership in the country that has them in their stockroom as NOS. I've found about 50% of what I need through Part Voice that has been discontinued by Toyota.
Good Luck and let us know what you find!
1982 SR5 Pickup RN34 ~bought brand new 11/81 - modified 22R with go fast goodies