Spectora.

In their words

• The $80M Deception—How Kevin Wagstaff Walked Away and Won Kevin Wagstaff co-founded Spectora with his brother Mike, starting with $2,500 each. Spectora is software for home inspectors. When an acquirer re-traded an $80 million offer at the last minute, they walked away. Wagstaff's point is that an offer is not a deal until the money is in the bank.