rusty/cracked outside drain to septic

I'm a first time homebuyer and I'm considering this house with very minimal issues. However - the basement is damp (it needs to be sealed - old concrete sinder blocks) but my main concern is the main sewer line from the house that is right at the foundation outside. The house has public water but septic sewer. The pipe, though painted at one time, is showing rust and fissures on it that I would account to the dampness in the basement.

If I purchase this (as the homeowner is selling As Is) what kind of costs will I be looking at? The pipe looks to be the old galvanized pipe that is about 4" diameter that the plumbing runs into. It does have a cap on it as well (thus my thinking it is the main sewer line). What kind of repairs would need to happen? I am thinking of asking for a reduced cost with the reduction emulating the cost of repair. Any thoughts?

I would recommend a thorough inspection of the entire septic system, including that pipe, and before going much farther. Replacing that pipe would probably not be all that expensive, but you might first want to be sure it has a properly-working place to go!