In that sort of condition, it would certainly cost a fortune to restore these.
As was previously said, if they look this bad on the outside, they aren't worth messing with.
I don't think they are worth half of what they are asking, plus finding someone who could properly fix and restore them would also be difficult.
If you can do it yourself, then it might be worth taking a risk on them, but only if I could inspect and open them up first.
Even then, i would still try to get them for half that price or less.
Old gear that hasn't been cared for is more than trouble than it's worth, literally.
Cheers, Phil