I am currently looking at buying a home and it's an older home that has been mostly updated. Except for of course, the plumbing. The basement still has the old cast iron pipes for the sewer... Would this be very expensive to replace. The house has about 1500 square feet of living space. I know nothing about this type of work and would like to know a round about figure before I decide to buy. IF anyone could help it would be appreciated. Thanks!

There isn't any one, no matter how sharp he is, that can estimate your job without being there to see what he's up against. Get three estimates and average them out for a ball parki figure. Also ask if there's galvanized water piping because that's will most likely go bad before the cast iron does. Good luck, Tom

I would ask is there a problem with the pipe, my parents house has the cast iron in the home ( replaced underground from roots years ago)
But I estimate that those pipes will still be great when I am long gone.

My home about 25 years old has cast iron drain all the way to the septic tank, and they are still great.

If they are leaky but just because they are old, don't mean they are bad.
As for as the drain pipes.