I owned a 85' n/a auto, main thing I would say about it was, you could pour sand in the engine and I wouldn't be surprised if it still ran

Mine was VERY reliable, only major repair I needed was the tranny rebuild, so watch out for that... they like to go after 100,000+ miles. If its in perfect shape I would pay 3,000 at most, the one your moms looking at has really low miles, you could probably talk them down farther.