The tree has gone bad and leaking antifreeze. How long and how much to replace? on 2003 Ford Taurus

My serpentine belt slipped off. I heard it squeaking but had no idea what it was. A friend said it was a leak in the tubing that caused it. I spoke to a mechanic and he said it costs a few hundred to fix. Just want an honest price.

Asked by for the 2003 Ford Taurus
Bring it to an honest mechanic who can actually see what is wrong and get a written estimate.
Thank you. I had it towed to a mechanic and it seems my water pump needs replacing. The shaft broke and thats why the serpentine belt popped off. Hopefully thats all I need replaced. It was quite expensive. $457.34 to be exact.
If it was done right , then it was.