Have you tried an independent shop that specializes in toyotas? If this is a common problem, it is the type of thing that an independent shop may have seem before and figured out how fix at a more reasonable price. I would make some calls.
No one was attacking pweber’s problem. He was just unwilling do do anything about it except wine. Multiple suggestions were made and he just did not seem to want to do his own homework. We are here for suggestions, not going over to their house and making everything all better.
A tiny bit of legwork can produce a seat. A local yard, even with use of a parts locator, may turn up something even cheaper than this.