It certainly works when you're selling to a business and you're showing how you can take away some real pain, or make them some real additional revenue. I have

It certainly works when you're selling to a business and you're showing how you can take away some real pain, or make them some real additional revenue. I have gone in with a demo and come away with a deal for real money. Then we built the real product around that customer's actual needs, which made it dramatically better than we could have by just guessing in advance how they would use it. Edit: Also see just about everything on Kickstarter, where people often pay real money for things that don't exist yet.