I've released DevBox 1.3.0 and wrote a blog post about it: https://dev.to/gdotdesign/devbox-130-3n35
With this I've implemented a web application version with subscriptions so DevBox from now on is also a SaaS (2.5$/month or 20$/year).
Also, I've released 10 tools to use for free. I hope this will drive up conversions.
I'll be running some ads now on Facebook and on Codrops and possibly Smashing Magazine (the last two are closer to my target audience).
Since the last update I've made 7 sales (about $175) which I'll use for advertisements.