Take out what you spent fixing up the bike and a small fee for selling it for her and give her the rest. Generally it is illegal to make money selling someone elses property (this is the crime of conversion). In this case you acted as a sellers agent though, and thus in equity should be entitled to some compension for the time and effort you spent selling the bike. Note: their could be a fight over the cost of the repairs you made. The repairs could arguably be considered a gift, and thus you would have no entitlement to those costs at all.