To be honest, we don't see a lot of sewer pros hanging out in these forums. However, it's possible someone might give you some input on this, but I just wanted to warn you in case you might also want to look for a dedicated plumbing forum where to post this.

As someone who has just sold an older home with many desirable features beyond some expensive repairs that needed done, I can tell you that you are under absolutely no obligation to pay for that repair. If the buyer wants your home badly enough, he or she will pay the price. If you had other buyers interested or if the time from advertising to a contract was relatively short, you could definitely try again for a new buyer if time isn't critical and you want to stick with your asking price. Also keep in mind that $10K one way or the other isn't a lot when selling many homes. You could split the difference if you were so inclined to work with the buyer, but again, you are under no obligation to do so. With a house this old, the buyer must have known that aging and major repairs were a distinct possibility. Best wishes.

Just a homeowner here. I had an old home with a 150' 4" line that needed every other year or more root cleaning and I saw roots pulled out. I don't know anything about your pictures, but I certainly can't see ANY roots in there. I would tend to think that those pics show a good clean line. Assuming you hadn't needed regular (or ever) line clearing then everything is good.

I own a 1948 house and just replaced 3/4 of the original main sewer line. It had cracks and roots and was a constant problem for me.

Cost? $2700.

@anglophilia my goodness, that’s a much more reasonable price. That was excavation and re-piping? Where are you located? I’m in Kansas City

Not knowing how long the sewer pipe is it would be impossible for anyone to tell you if that estimate is a decent one or if you are being ripped off. I would ask for an estimate from other companies. The price does seem a little high but prices vary on area. Edited to add price would also depend on method of lining. Here some companies insert what is basically a balloon of material that is inflated then heated with steam which hardens it. Other companies use solid materials like plastic pipe.

I’m in a Louisville. Not sure how long line was but I only have 1/4 acre lot.

I'm not a contractor, but I have a couple of observations:

1) I don't see any photos that indicate a collapse of the line or obstructions, or any significant root problems. In fact it looks pretty good for a sewer line of that age.

2) You don't mention any sewer problems, so I assume you haven't had issues (and the sewer looks clean/dry with proper slope so that there are no low spots accumulating waste/water).

3) I think the bid sounds high, and I live in an expensive metro area.

4) I would get a second (or third) opinion. Maybe a good home inspector or independent plumber could give you a neutral opinion, rather than hearing from folks who want to sell you their services.

5) Instead of letting the buyer use this as leverage to get a $10K concession from you, consider offering to pay upfront for several years of a home sewer repair warranty in case this becomes an issue.

I recommend the warranty option as suggested. In my area, the gas company has an affliate offering a warranty program for sewer lines at a very reasonable cost. In my experience, many of the issues found at inspection are upgrades or investments rather than necessary repairs.
I have a house where we had a quote for lining at $3800 for 20 (?) feet then $40/ft additional distance. Replacing the pipe and installing an exterior cleanout was quoted at $2500 by another company. The actual replacement is cheaper but does destroy the yard.

I echo the above comments that if you haven't been having sewer problems, the new buyer isn't likely to either in the immediate future. If the buyer really wants this house and you aren't desperate to sell, play hardball with your asking price and don't concede that much money for a non-issue would be my thought.

I recently got to see the entirety of our 180-foot ABS sanitary sewer line via cctv with water running continuously. My inspector said aside from a slight dip at one point it was fine. (Certainly no cracks and roots as on yours.) On the contrary, the city said it had to be replaced as a condition of receiving a permit to build a new home. No liner permitted.

As noted by others, you could invest in an independent cctv-assisted quote to give you guidance on what you want to do with the offer.

BTW, first time I've heard of such an inspection on a resale home. (Not a bad idea, actually.)

It depends on the length of the pipe that needs to be replaced but it's usually anywhere from $60-250 per foot depending on the region and who is doing the work.

Annie-

Sounds like a great resolution, and glad you didn’t get ripped-off.

If you're going to do it, great. An alternative is to sell 'as is' which puts the responsibility on the buyer.

Older home and clay tile sewer - there will be roots. Get over it. Offer to run the drain to clear roots.

If the sewer has collapsed or has similar issues, that's different.