What Does "Reasonable Offer" mean?

I've heard others say that their stuff isn't for sale yet they get asked frequently.....then respond with a sky high number.
I don't even play that. Why? Because to me, I don't feel that everything is for sale. Money means nothing to me if I don't have what I want.
No amount would buy a car that I own and really like even though I could duplicate it with the money from the sale. Maybe it is because I'm a person driven by principles, not money.
If I promised a guy that I'd hold a part for him..... and at the end of the day when he returns I'd sell him something for ten bucks and a guy walks up right afterwards and offers $20, I'm going to honor the first offer. Yeah, I take the risk that the first guy may skip but a man's word should be worth something.