I gave up sending emails because by that stage, they had already decided they weren't going to pay for it. I resend an invoice on day 3 and if I don't get any response to that, I open a dispute on day 4.

Sometimes life happens and eBay is the furtherest thing from their mind. Stuff happens. People die. People go to hospital. People get called away unexpectedly. However, when you can see they are still actively buying, you know that stuff hasn't happened and I am happy to flog them with a stick.

My current non payer isn't still buying, so possibly has had some kind of family emergency, but I'm not running a charity service. If they come back later with a reasonable explaination and still want to buy it, I'll probably give them another chance, but I'm not expecting to hear from them.