Set up a landing page and way to preorder your product. You could also use something like
https://gumroad.com/Then, go back to the people you talked to and ask them to preorder. "Yes I would probably pay" doesn't count. Make them pay. If they pay, great, talk to a few more people and repeat the process. Maybe aim for about 10 people or so?
If they don't prepay... start listening closely. You should get some good feedback on the idea.