While I tend to feel that yard/garage sales are usually just someone elses "cast-offs", I keep having people show up with "I saw a great old fiddle at a garage-sale, and I thought of you!" (Well, thanks...I guess....)
One of them actually bought the instrument and had me set it up for him. Very nice amateur-made violin, in virtually mint condition, and he got it for $2 (yes, that is a two, with no zeroes.) He doesn't even play, but he wouldn't sell it to me. In spite of this I have no intention of beginning to cruise garage-sales, hoping to strike gold. The odds are just too slim. (I don't play the lottery, either...)