well you have a couple thing to consider....
there is some family value, only you can decide what that is worth. if you feel like holding on to it for 30 years it will be worth more then you paid for it.
in my neck of the woods the cars are worth about 2 grand for a nice clean one. they seem to get all kinds of loose body parts with age and rattle/squeek. so tha actual value of the car is not 5g's to the open market. there is a wealth of horsepowr that you can make with the sum of parts you have, and you could make the "Joe Dirt sleeper" real easy. there is nothing worse then getting your doors blown off by a mullet blasting loverboy through the t tops
so, if you are looking for an investment, its gonna take a ton of years before the car is worth more then 5g's. if you want to keep it in the fam......go get it.
Good clean ones where starting to rise in value before this fall. I am sure they have dropped some now. Seems like the mullet owners of the late 80s where interested in them again. I did have one and also a couple gta's.