Non paying bidders are such a pain! This is the way I handle the process...
I state in my auction that payment is expected in 7 days and to contact me in 3. If I have not heard from them in 3 days, I resend an invoice, which I have preset with my payment terms. If I still have not heard from them in 5 days, I send them a gentle reminder email that I have not heard from them, and to kindly let me know their payment intentions. On day 6 I send an email reminding them that on day 7, since I have been unable to contact them I will have to assume they are a no pay. On day 7 I open a dispute. And on day 15 I close the dispute and send them an email stating the item is no longer available for them to purchase and relist. I am always very, very nice and I think 15 days is generous. I have only actually left non-payment neg FB like a couple of times. Most people eventually pay, and I have even had one person come back after neg FB was left and actually pay for the item...like 20 day later! You can also do a second chance offer to anyone else that has bid.
Of course, these are my rules and I hope Ebay approves.
Sorry that has happened to you! 😞