Pay with something other than money
I love the idea but $7 a month is not worth a lot to me. One idea for the future, maybe try and do a partnership with a magazine company like Hurst or New York Times. You can offer them my data in exchange you give me a magazine subscription.
The net value might be the same but you could give me something that would cost me much more than $7 a month
Mathieu Maes commented
Do you think a magazine will see an individual data-set as valuable enough to trade it for a subscription?