AS stated earlier, the TRD BBK kit uses slotted 332 x 35mm rotors. The calipers that go with it are StopTech ST-40 4piston calipers.
The kit pictured uses slotted 355 x 35mm rotors. I'm not sure which calipers go on it, either the ST-40 or ST-45 calipers, either of whcih are still 4 piston.
The rotors are available separately from StopTech's independant distributors and anyone can get them. The catch is the calipers and the caliper mounting brackets. For the calipers, you have to choose whcih caliper piston arrangement to go with since I believe StopTech offere multiple piston arrangements for each of their calipers to properly balance out brake forces across the axles. And the mounting brackets are specific to each vehicle application. And I'm not sure that the calipers and brackets can be ordered separately..