I'm not sure about the Silver ones, but i know for sure you cannot buy the black or gun metal ones at the dealer. I have tried this, I even had connections with some of the people in different dealerships. They require a VIN from a Trail Team FJ, Which i was able to easily obtain. They then required me to have a reason for purchasing them. (there had to be a logical reason) I told him to tell the guys at TRD that i had some nasty curb rash. TRD then required a claim from my insurance. It's a ridiculous mess to try to snag these brand new. Toyota lost out on making some money from me and i care care less!
The silvers should be easier to get but good luck!