There are enough litigation examples on this issue around to suggest their fears are well placed. A confidentiality agreement (also called a non_disclosure agreement) and followed by a letter of intent is the two step process for allowing a business concept owner to establish a new business relationship without losing control of their business idea.
A Letter of Intent is usually used in the beginning stages of a negotiation to get "good idea" of what the buyer and seller are each after. It is not required, and quite frankly, is not used in most transactions. However, a LOI is a good document to use _ especially if you are looking to purchase a property for substantially less than the listing price. Let's look at when the best time to use Offer to Purchase. Remember, this is the formal offer, and is legally binding once signed by both parties.