When you put a BIN on an auction as soon as the first bid goes in the BIN disappears. Your starting bid must be the lowest price you'll accept for the item.

If the buyer hasn't paid you can cancel using the link below.

https://www.ebay.com.au/help/selling/getting-paid/resolving-unpaid-items-buyers?id=4137

Don't let the buyer pay by any other means than Paypal/Credit card/ G Pay, which will be processed by eBay through Managed Payments.