i think i made a mistake...

a few months back, i looked at a bone stock 89lx convertable with only 70XXX miles. because it was an automatic, i really didn't go after it. the car is/was in excellent shape, new top, and was maintained by a ford garage mechanic for the last 10 yrs. i had forgotten about the car until about a month ago when a friend of mine bought the car for what I believe was around $5000 give or take a few bucks. what is a car like this worth? the reason, i'm asking is because the guy who bought the car never holds onto anything for very long and probably will be selling shortly. like i said car is in great codition for being 100% stock.