The thing about trades is the person has the right to ask whatever they want for an item. It is buyer beware when it comes to how much an item is actually worth. Always check other TP posts as well as the Wiz and the Auction Genie before making an offer.
Even if your offer is extremely good, there is no guarantee that a person will accept it.
I am sorry you spent so much
At least you didn't accept an offer on an item worth 550K for a Roe Sushi because the TP said it was worth much more when you could buy it in the Wiz for less than 15K. I know some people who were suckered by that ploy.