I guess it depends what your selling but my NPB's are not pranksters. They're either complusive bidders or pattern addicts that get in over their heads.
I don't even break a sweat over it anymore. Honestly, it's just a waste of energy. It's all a routine thing for me. If they don't pay within 2 weeks and don't contact me, I send a reminder. After 3-7 days I file with eBay if I haven't had a response and on the 8th day I close it out and block the bidder.
I am just glad though that they are now refunding the auction upgrades too. It's about time!