Frankly I wouldn't worry about the negative feedback. Anyone who is an intelligent buyer *reads* the feedback and sees what is there.
So if I see someone with a mostly positive feedback and see one or two negatives, I can get a feel that the seller is likely a good one and this is just a case of the poor seller having to deal with yet another person who has champagne tastes on a light beer budget.
I never lost my faith in humanity. Can't lose what you never had right?