You have some great thoughts there.
As far as the feedback goes, she already left me positive feedback, so she can not retaliate against me. Also, I don't want to do this because of revenge. If I leave negative feedback, it is because I feel that the Ebay community must be made aware of her warped set of values which somehow justifies her charging an excess $18.00 and putting it in her pocket, unashamedly.
Furthermore, I sent here several emails trying to appeal as kindly as I knew how until it got to the point where it was obvious I was getting nowhere. It was at that point that I gave her the ultimatum that if she didn't at least refund a good portion of that money, then I would post negative feedback. Then I gave her a deadline of 5:00pm today, but she remains stubbornly defiant.
So the worst she can do is to respond to my feedback in her profile, but then I will post a rebuttal and still get the last word (or so it would seem)