I’m not completely sure how their pricing works but @csfalcao posted that he tested with Digital Ocean’s $5.00 a month droplet and it worked perfectly:
The Discourse creator said that the Digital Ocean “droplet size” you need is based on how many “concurrent logged in Users” your app has here:
https://meta.discourse.org/t/is-digital-ocean-10-month-package-good-for-discourse/33218/15