Originally Posted by TheWollard
Is the seller somehow running a scam? They have volunteered to visit a bank and get the 2nd flagged $100 checked with the buyer. Impression of seller is that they are just a regular family. Not mustache twirling villains.
If scam artists all looked like Snidley Whiplash they'd be easy to spot and there'd be no scams.
Tell them you'd like to go with them to the bank that flagged the bill to find out why they flagged it - banks do make mistakes - though they probably passed it on by now.
Get the remaining bills back. Tell them you'll do the deal if you each eat $100 and do the deal at their bank with a cashier's check and don't leave without the signed title.