I'd heard on SpeedVision that Frank's price to let Button go was more like $90 million U.S.. If that indeed was the case, I'd be very surprised it Button goes $18 million. That said whoever pairs with RB, Button or Sato, will wipe the floor with him.
Hope that Anthony Davidson can get a ride at Williams next year. It will be interesting to see who is the faster of the two: Button or Barrichello? Button has not had a fast teammate in the last couple of years - Sato or Villenueve. Barrichello has had the fastest teammate ever for the last couple years. I believe Rubens will be quicker in race conditions and Jenson quicker in qualifying.
You're living in a dream world. While Sato's had appalling luck this past year he's certainly shown speed matching that of Button. Rubens won't be able to hold a candle to Button. I'd take David Coulthard over RB any day of the week if you're looking for a fast mature driver.
You forget that Button was the same guy that got mopped up by Fisi a few years back, i think RB will do just fine.
I dont recall Sato qualifying anywhere near Button this year. I believe he was much closer last year. This year he is several tenths off. Besides I think Rubens is highly under-rated - he may look ordinary next to Michael but he is still faster than all except perhaps Raikkonen, Alonso and Montoya. Anyway we will only know the answer next year.