I didn't have a problem having a cambelt, and major service, carried out at a toyota dealer and at the uk fixed price (which is a lot) but at least it wasn't; we will do the work and bill you later (at an extra £10 per hour), or oh no we dont touch supras or GT4's.
The problem is they garage gets scared, when there blokes are usually used to changing oil on yaris, and corolas, etc..
Personally I can't see the problem, while the car might seem complex the service, and other minor tasks are no diffrent to any other car.
While it's nice to have a Toyota stamp in the book, you will find that a company that does lots of work on supras, and the like, would be a better bet anyway.
Thats my 2p hope it helps.