Offer to purchase

[peacemakercoins]

I received an offer to purchase from eBay for .34 cents less than my asking price of $9.34 so $9.00 I accepted it and sent the buyer an invoice.  He sends back a note saying he put a note on it that he would not pay shipping.  Which now lowers the amount I'll receive by $3.00 which I never would have accepted.  When I brought up his message sure enough he had attached a note.  At first I was going to honor it and just eat it.  But this guy is scammer and now I'd rather not giving what he's angling for?  What are my options or do I even have any?