got my not so shiny new to me 1987 Bayliner in the water for the first time last night... I have a leak between the transom & hull. boat mechanic says the motor has to be pulled to put a new gasket on it. he gives me a price of 300-400. is this a reasonable price?

$3100 for the boast , $80 to dewinterize... $358 in title/tax fees, now another $400 for the leak... arrrrgggghhh!