I agree with Curtis Nq and Kunj K. Everyone is using the exit pop-ups nowadays and yes they can work to bring in more sales but if it seems to desperate it won't work. Plus also many customers may get annoyed if there's too many pop-ups when they are trying to leave the site.

I'd say, be creative an offer something for free to get an email sign up instead of "giving away" your product for just $7 bucks. If you offer a free product for a sign up, you can follow up with them and potentially make a sale for your product or an affiliate product at a later stage. (or make even more than just 1 sale if they keep being your subscriber)

Hope it helps

Cheers

Reno