She knew you where selling and agreed to buy it so why would she be offended you asked for the money.
When you buy from an individual you take it on trust it's what they say it is. If she wanted guarantees then she should have brought it from a shop.
I haven't sold anything but given things to charity or advertised things on can't remember if it was called buy nothing or pay nothing local site . The freezer and separate fridge worked that I gave to a charity even had the manuals which I taped to them. I had new kitchen so they wouldn't fit . Things on the pay nothing site where old but still in good condition. And people where happy with them.
If you bought a potato salad would you expect potato?


