How about a 1 day trial or at least an example email on the page? The concept is great, but i'd be more comfortable spending the money on the subscription if I had some idea of what I should be anticipating in my inbox the following weekday.
It offers a 30-day money back guarantee, so you can try it if you want without any worries. Shoot me an email though, and I'd be happy to give you a look at some sample leads. kesler@freelanceinbox.com.
*On Thursday, Freelance Inbox will have a big announcement that will alleviate concerns like yours going forward. As fair warning, you might want to claim a spot early :)