what about paint and interior? Honestly I never understood the anxiety about the dried out rubber. Literally the first thing we tell any new owner of these cars to do is replace all the old junk anyway. The good news is with a low mile car there's probably no to little rust on the hardware, parts are original, so you don't have to worry about shade tree hack work.
On top of that paint and interior are what really matter. It costs what? $1,000 to replace all the rubber on these(including tires)? Ever price out a full quality paint job? How about New carpet, headliner, seat covers, and source all the various bezels and plates that careless owners manage to break and gouge to shit?
I get that, I'm just trying to shatter the "barn find" illusion that the car hasn't aged just because it wasn't driven much.
My 130,000 mile 1997 has been pretty easy to work on, because it's not all rusted up. The paint is shot, and that lowered it's value to me, just as buying a car with good paint and interior would have a lower value if I could see I have to spend another chunk of money and time on it to bring it up to driving condition.
Not saying the car is worthless, or it's a $1000 car or anything. Not having looked at it but assuming it's clean, cared for, and had been well maintained (oil changed every 3 months so it doesn't sludge up, etc) then I'd put it in the $3-5000 category. There's a guy in Eau Claire, WI selling a 70K 1996 Thunderbird for $13,000, and it'll never sell. My guess is he doesn't really want to sell it, but that's just insane. I love these cars as much as anyone here, but I just can't see spending that much on one. The guy selling his big bore Mach1 engine'd 32V for $2500 is I think a very fair price, and I'd buy that much faster than buying a bone stock one with low miles. It's closer to what I personally would want out of a car.
Since this guy is buying one from a family member, and doesn't want to screw them out of a nice car, I'd say give them $3000 or so and enjoy the car.