How good a deal is this?

since he already knows so much about them, i'd guess he also knows they'll need more parts to fix than they're possibly worth ? For each laptop you can offer for sale you need at least one (good/working) battery, one charger, and one optical drive (parts easily removed or commonly missing in those type situations) plus all the other necessary ingredients, good screen & video, sufficient memory (256 is a bit lean these days), decent keyboard, working touchpad, legal operating system, etc. I actually think you'd be buying his headache.