I don't see him getting 30k. Not for a while anyway.
The seller is in Mass. I wonder where has the car lived it's life? Snow country or in the south?

FWIW, I paid 15k for my 88 in 2001 on Ebay. It had 41k on the odo.
As it looked then... a Fla snowbird car.:



As it looks today, with 133k on the odo:



Be surprised if I'd get over 5 or 6 today......and I spent over 4 grand on it last year.That's why it ain't for sale. I'll get some of that back in smiles if not dollars.

It's a clean looking maching tho....Hope he gets his price.
Say, were the wiring harnesses an issue in the '91 124s? Might still be wearing the original if so.
Final thought. Before I paid 30k for it, I'd check with my insurance co to find out what they would pay if it was totaled or stolen. Might have to jack up the coverge.