Not commenting on Bill's situation at all. But just as a general situation, if I ever decided to go to garage sales looking specifically for cheap PM's (I've never done that before), and let's say I found a sale that had a big collection of silver coins for sale. I would offer them the least I could to acquire the coins. I guess I am a bad guy for that. If it were a friend or family type thing and someone came to me and asked what the value is, that would be different and I would direct them to the best paying coin dealer I knew. In this modern age if someone is too lazy to check prices online, or to pick up a phone book and call a few coin stores, then I believe it is my obligation to accept the universe's gift and buy the coins cheap. The only exception to this is if the person selling the coins is obviously mentally ill or otherwise mentally handicapped.
At a random garage sale, I see no reason to educate the seller as to an item's worth. That to me seems to be the fun of a hunt at a garage sale: to get a crazy good deal. Usually these online stories involve some sad fact like the family was selling the coins to pay for a young kid's treatment, or some old lady was about to be evicted, etc, that simply seem to make it more evil to buy the stuff at the price they offer it and brings out the moral good guys and gals to flog anyone who says they would take the coins for a cheap price.
Back when I was on the CRHing forum these stories popped up all the time and it always involved a big debate on the morality of buying stuff cheap vs. paying what a dealer would pay (or close to it). Who's to say what's reasonable or not?
PS I believe a real coin dealer should follow the ethical guidelines as laid out by the various coin dealer associations of which most legit dealers belong.
Just my opinion.
Jim