As much as I am a believer in markets and competition, if they did enter into the acquisition in bad faith then it sounds like you need to talk to an IP lawyer. It is a little late for should haves, but I would have had a rider in the NDA that failure to acquire carried a monetary fee 10% of acquisition sounds about right. It may scare off truly interested parties, but it will surly weed out anyone acting in bad faith to acquire market segment knowledge. A non-completion rider is not as unusual as one would expect.