Buyer with zero feedback who never pay and never reply. I have at least 5 such purchases every month and all I am able to do is wait for 7 days then open "non payment case" and wait seven days and then close case and relist item.
Most of such buyer claim "they will send DD or MO or Bank Transfer" right after purchase and then stop replying.
I am fortunate that I do not received negative so far but clock will tick and I will be in trouble just like you any time.
P.S. Just this month, I sold a vintage watch and buyer wrote me dozen mail that he was busy, his bank have problem, he sent DD, then gave DD number and lastly he will ask his sister to pay and pick up which never happened. I never received payment and never got reply from him afterwaords....what I will do but blame myself.