Say it was a 2007 Lexus with the sport shift transmission... then probably $5,000-$6,000 if only the transmission needs to be replaced. If the engine needs to be replaced also, probably closer to $12,000, assuming they use all new parts.
Rebuilt parts will be cheaper. Older cars will be somewhat cheaper, but these are the two most expensive things to repair.
The prices I gave you are estimates. For all I know, some of this will be covered under warranty if your car is new enough and has the deluxe warranty.
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