If the price was agreed upon then the seller backed out as you were about to leave your house this is foul. I’ve had someone tell me they sold it to someone else as I was on my way to get it. I like the agree to the higher number and promise to pick it up in a week then delay it further if you can then ultimately backing out move. This is what I call getting “Craiged”. There are a lot of “Craigs” out there.