I'm going to assume that since you're not actually a business that you never gave them a receipt when they handed you their laptop either?
Wipe the drive, sell it, take your costs out of the total you get and hand them whatever's left over. Can't really get fairer than that.
Wipe the drive, sell it, take your costs out of the total you get and hand them whatever's left over. Can't really get fairer than that.