Have you tried Checker/O'Reilly and NAPA?
O'Reilly shows rebuilt caliper from Beck-Arnley, Wagner and Cardone. I used the Raybestos rebuilt caliper and they work fine. The pads aren't as good as Toyota, but the price was so much cheaper than Toyota that you could buy them and still come a lot cheaper.
'91 Toyota Pickup
'09 Kawasaki KLR650
'12 Gunnar Rockhound 29
“Anyone who believes in indefinite growth in anything physical, on a physically finite planet, is either mad or an economist.” -- Kenneth E. Boulding