Didn't know offers/counter offers did NOT include shipping

Hi,

I'm the buyer in a sale, and while making offers, I was not including shipping in my offers (thinking I needed to add $75 for shipping to it, based on estimates).

The seller made a few counteroffers and their final offer said "$$$, shipping included, final offer" - so I accepted it.

Problem is, Audiogon tacks on the $75 of shipping to his "accepted offer" and wants me to pay.

I've tried contacting the seller (0 feedback) about the situation, I guess I'll have to call them later today to discuss. A shame of a mistake.