Welcome to an excellent forum where people share the same interest. Like many forums you are going to get many answers, you just need to decide what works for you.
3 hours isn't really that far in my opinion. I'm not crazy about the sellers name, but he has a great feedback rating. One thing to keep in mind is although it is a "binding contract" if the seller is fair he may let you out if you get there and decide that the vehicle isn't for you. I know I would, all I'd ask for is the listing fees. Considering the hail damage and the fact that I see one good size rust spot on the left fender I'd say $3,000 is a little high in my book, but its hard to tell for sure with little info and these pictures alone.
Myself, I like to be as gentle as I can with newly acquired hardware, sometimes when you attempt to fart around with these you have this thing we call the snowball effect. Now that cooling system that may have gotten you home suddenly has a leak.
Many states offer cheap transit plates for out of state buyers to get vehicles home.
Best of luck!
Dave

__________________
Currently driving a very clean 1985 300SD from the West Coast.