Great idea, great app.
You should consider making it a proper osx app on the appstore and selling it for a 2$.
If you are interested and would love some help, let me know (https://sideproject-help.com)
You can have both. Why people will pay for the app when you can download it for free ? We will see it as a donation. I always start by using FLOSS and if I stick with the software for more than one year I send a donation. Having the app on a store is a way to achieve that. Thank you for choosing to open source the application it matters a lot for some of us.