Ask HN: Where to Run a User Survey?

We are planning our first implementation (proof of concept) but need to validate our idea for a healthcare startup before beginning work. The problem is we don’t have any users yet.

Can you recommend where we could run potential user surveys to get feedback on the idea? We’re looking to avoid spam and are seeking earnest users to generally understand the pain points of the general public.

We’re not averse to paying a small amount to compensate the users for their time.