I offered him just over 20% less than his asking, hoping we would settle on something close. He didn’t care to counter and we left it there.

Consider yourself lucky. Seller is off his rocker at that price, in this market.

A couple of really special 930’s for sale here....a little more money than the $115, but really not that much more....and both are special in slightly different ways...no affiliation except they caught my eyes.

https://autokennel.com/

https://autokennel.com/1977-porsche-911-turbo-carrera-coupe-2/
And

https://autokennel.com/1976-porsche-911-turbo-carrera-coupe-2/

He's priced strong, but not exactly off his rocker.
It's a 6 figure car with the paperwork.

https://bringatrailer.com/listing/1983-porsche-930-turbo-8/
https://bringatrailer.com/listing/1988-porsche-911-turbo-15/
https://bringatrailer.com/listing/1986-porsche-911-turbo-56/
https://bringatrailer.com/listing/1989-porsche-911-turbo-27/

I’ve checked the BAT historicals. Cars almost always sell there for more than they would bring in the regular market. It’s the result of auction mania. For every six-figure 930 on BAT, there are 10 more that are just as nice that sell or don’t meet reserve for way below that, so who knows what is going on in a particular auction, at a particular moment in time.

Plus one of those 4 examples was a 1989, which is in a whole different league than any other 930, except maybe a first-year Series 1 Turbo.

All the big money 930s on BAT are almost always really low mileage, have excellent provenance, are unique in some way, or have some combination of those qualities.

Are you thinking of bidding on this car?
https://bringatrailer.com/listing/1986-porsche-911-turbo-60/

Sold for $82k.