Congrats on creating a side hustle while completing grad school. This UX is far superior to MTurk, but as others have suggested, the price point is definitely higher. A few questions:

1)"You can easily invite participants for follow-up studies at no extra cost." So, I can re-contact them through your platform OR I gain access to their contact info?

2) What % of customers are repeat buyers (multiple surveys)?

3) What if I want to recruit childless individuals? The current audience-checker doesn't seem to offer zero as an option.

4) How automated is this process for you? What % of customers require a touchpoint or multiple touchpoints?