Don't condem all dealers for the likes of a few bad apples.  We have done many of these warranty repairs and the cost ranges $150-400.  Reason for the range is that some customers want us to R & R the engine from the unit.  This can double the cost, especially if they also want other things done, ie; sharpen blades, level decks, check and hydros, etc.  Most short block work run about 2-2.5 hours