From the photos the foundation seems to have major issues.

[Not only is there foundation seepage along the bottom where the basement floor meets the basement bricks which you can see here...

... but there is brick degradation all the way up the foundation wall (which you can see from the peeling paint in an inconsistent manner instead of in a consistent manner - meaning some bricks are rapidly eroding more than others and have lost their protective ability to be water resistant

At this point it’s beyond the $25k cost of just digging down and replacing weeping tile and adding a vapor barrier (with an additional $3k sump pump and $4k recommended back valve).

If the bricks have lost their permeability and they’re nearing 100 yrs old, there is a risk of structural compromise, the foundation shifting (if it hasn’t already), the foundation cracking (if it hasn’t already), and a need for foundational reinforcement.

So if we take $40k for the exterior work to be done (up that to $120k because the front porch with its columns and roof need to come off to get full access to the front foundation wall, plus the back enclosed porch extension needs to come off for the same), and another $120k for underpinning or other reinforcement, including a complete gutting of the basement and renovating it after, and, well, the costs start to add up.

And if the brick walls have been compromised further up, underpinning and water proofing it are just part of what could be needed.

I think there’s more to the story with this house than what we’re aware of. The buyers are likely aware of this (and are willing to sink the money into it to bring it up to par to what they otherwise would’ve paid, just to have this subway/danforth-friendly location, and the owners are likely aware of it and know this is the price to charge for it to sell).