Who is he going to sell it to , except to you? Are you located in the
pacific NW? If so, junk Vanagon values ar higher then most elsewhere. He
may know where he can sell it for more than regular none running vehicle,
values.

He can get $50 from a tow truck that is taking it to the crusher. Other
than that , it is just  another non running vehicle. A fire ? Surley it
needs more than just the repairs he outlined. You can check the overflow
tank for a 50/50 antifreeze concentartion.If it  is less than 50-50, it
probably has a head gasket leak. Check the tires.If they only inflate to
35 or 44psi, they are incorrect tires. The owner probably didnt put the
money into the Vanagon which he should have. These are negotiating
points.Does he have a title?
How did he get it?
I would only give $200 max for any non running vehicle. The seller may
say "the parts are worth a $1000" They may be, but they need to be removed
and sold.You would now have to find the buyers.If he wants $1000 , he can
part it out. He may just want a few dollars and the parking place back
that the burnt Vanagon is taking up. Offer him the tow job to take it to
your house in addition to $200. When you get it home, you will see all the
problems with the individual parts that you didnt see at the garage.Little
scrapes and broken items.Your justification of $200 will begin to get
verifired as a good price(to you).Just my opinion, and that is what you
asked for.
Good luck, Roger