You wouldn't want someone wasting your time, so you need to offer something in return.
Share something truly of value to them - reports, research, etc. - related to your target markets "pain point". Ask to chat with them 5 minutes to gather further information - be clear that its not a sales call. Be prepared to ask some good questions that validates the need, and if appropriate, ask for permission to follow up with them to share additional information that you gather from other conversations.
Take such information, create a MVP, then ask if they would be interested in validating the concept. At this juncture, many would ask for payment to participate if the validation process yields significant savings / value generation for the participant.