Hi, I buy and sell about 70 items per month on Ebay, and I have only had about 6 non-paying bidders. Usually they are new, and had no intention of paying or responding, or sometimes sometimes things happen, and they find they can't pay for whatever reason. But if you get no payment and no response after 7 days, file with Ebay. They will send a reminder to the person. Then, I believe, you have to wait another 7 days before you can close the transaction if they don't respond. I don't leave negative feedback until the last possible moment, I want to give the buyer the benefit of the doubt. There's really nothing you can do before the 7 days have passed, and if you didn't state differently in your listing, some people think that is a reasonable time to wait to make payment.