"How should I handle this? "
Add the buyer to your blocked bidders list and start the unpaid item process 4 days after end of sale and then close it 4 days later.
"It was not an auction, it was a buy it now so I do not have the option of a second chance offer to another bidder. "
It doesn't matter the type of listing you have. You treat all deadbeats the same way and file a dispute. One you close the dispute and have your final value fee credit, relist the item. Sellers are never obligated to make second chance offers on auction listings so the type of listing you have has no bearing on how you treat deadbeats.
By the way, set your buyer requirements in my ebay to block bidders with 2 or more unpaid item strikes in the past 12 months, have 4 or more policy violations in the past 6 months, who are in countries you do not ship to or who do not have a paypal account.
Non paying buyers deserve unpaid item strikes.