looking to buy a 73 450 sl c

Looking at a 73 450 sl that needs a fuel pump, everything else on it looks good and its in great condition, im just a little skeptical about the situation. Its a nice old lady who owns the car and it only has 105k on it, but i can't afford to have another hole in my driveway that im throwing money into. Does anyone know if this is a common problem or if once it is fixed it will likely be done or if it can lead to more extensive problems.
Any information would be greatly appreciated.