> How do you get quality feedback? In my experience people will often say yes when asked or shown a mock up but will not buy. You don't find out who will actually buy until they try a functional product.

Ask them to pay you based on the mocks. If they say no, ask why. If they say yes, take their money and give it back in N days if you haven't built your MVP. I've done this BTW - it works.

> You don't find out who will actually buy until they try a functional product.

You'd be surprised how many people have gross business problems that some well-placed code would solve and they'd be thrilled to pay you for it because the other options suck.