2002 Saturn SC1 Car runs on 3 cyl.

Hi,
A friend is moving and wants to give me their 2002 Saturn SC 2dsd automobile.
Mileage is 120k
He said he was told by a mechanic that only 3 of 4 cyl are functioning but that he has never experienced any issues. He gets 25 mpg local driving.
My question: What would it cost to repair and is it worth the price or should I just leave well enough alone or should I say thanks, but no thanks?

Thank you
Sincerely
Richard Kiernan