Sorry to hear about your situation.
Mine also went out this past January. I have a 2002 AWD that was exclusively serviced by the dealer. Lexus stepped up to the plate and paid the entire cost of a rebulit tranny and labor charges. I also had to get Lexus of America involved.

 

I just got our lexus rx300 back after spending $4200 for a rebuilt that is guaranteed for 5 years. I received a box of parts with chipped teeth on the planetary gears, and loose small gears that are supposed to be tight. There really was a problem with the transmission, and the shop owner explained that they replace these all the time at about 75K miles. We only got 73!

 

Man,you cant beat a 5 year warranty! What shop did you go too?