I had something very similar happen to me. A lady saw me out with my metal detector and stopped to ask about it. Said her husband passed away and left a pile of metal detectors in the closet. Could I come look at them, and help her sell them. Sure, I checked around, got her market prices and I even bought some of the smaller accessories.
Then she asks if I know anything about guns. Why yes, I do. She shows me a pile of surplus military rifles. Her husband was with the SBI and enjoyed collecting them. She says, tell you what, give me $100 and you can take them all... I thanked her, but explained that if I took her guns for $100 that I wouldn't be much of a neighbor. At a quick glance, she had a couple civil war long-guns. She also had a German Mouser with all matching numbers stamped with the swastika. A Japanese mouser, all numbers matching with the emperor's Lotus Flower stamped on it. And several other nice collectable long guns and handguns. I advised her to please take them to a reputable gun shop and gave her a few names, to have them appraised for insurance value. Who knows, maybe they will make you a reasonable offer on them. I so could have walked away with 10 grand in guns for $100, but I was a good citizen helping an old lady.
Anyhow, A few weeks later, a friend who bought a metal detector from her, said that she claimed I ripped her off. It seems that she thought the $25 bucks I offered her for 2 used rock hammers a sand scoop, and used find bag wasn't a fair deal. Used, banged up hand tools don't exactly hold much value. I asked her what she wanted, and she told me, I don't know, how much do you offer. I told her that I had $25 with me, but if that wasn't enough, I could come back another day. Mind you, all this after I made calls to several metal detector stores for her, and found her a cash buyers for her metal detectors. Plus I examined her guns and didn't take advantage of her ignorance of firearms.
I guess it's true, No good deed will go unpunished. Had I given her $100 for all her guns, she probably would have been happy and not talked behind my back. So much for being a good neighbor...