Actually, I still think the average is actually closer to 15k/yr... Regardless, on a 4Runner, I don't think the warranty will pay off. Major components like the engine and transmission are going to go WELL beyond the 100k without serious issues. The other little stuff, like some have had brake calipers, or various little things... Those are inexpensive to fix yourself. Both front calipers will set you back anywhere from $120-250 depending on which one you pick at the parts store.
I think the other major failures (gauge clusters, yaw sensors, sunroofs, etc) are actually a lot less common than we think. The folks on this site account for a VERY small percentage of the number of 4Runners that are manufactured and sold.
Ricky