It doesn't have to be a fake page, talking about a mvp where they can gauge who is interested in paying and what their problems are so they can concentrate in those areas. When confident they could even setup a simple paypal re-occuring sale system too.
A better(maybe?) idea could be to send out a survey asking what features people are interested in, whether they would be willing to pay for them, and how much if so.
It could be an option when you log in to the UI. I wouldn't mind it, as long as it isn't being e-mailed to me every week/month.
