Sounds like they were not happy with the price.
You can leave them neg feedback for failing to complete the sale and move on.
Not a lot you can do other than the feedback and reporting to ebay as a non performing seller.
If they open a dispute for non payment to try and get the neg removed call ebay and tell them the problem and why you have not paid and why you want the feedback to stay.
To call ebay click on Customer support in the top RH corner and then click on Contact ebay then hover your mouse over selling and then click on report a member then click on call us and you will be given the number and a code to enter on request.
