Yep, lots of options out there. One of my motivations for doing the project was to just learn how to provision a bunch of AWS services and make it reproducible

Yep, lots of options out there. One of my motivations for doing the project was to just learn how to provision a bunch of AWS services and make it reproducible. I might write a little shim so you can also just run the API as a standard Node.js app. At the end of the day it's just a JavaScript bundle and a single REST API method. Even with a service like Heroku, a choice needs to be made for what service to use to store the data (eg. postgres). Heroku's free tier is almost like a course-grained Lambda because the VMs spin down after a period of inactivity. I'm actually really excited about https://zeit.co/ https://zeit.co/ - check that out. In the long run, the hosting cost for this type of application should be pretty close to zero. People will choose their cloud/hosting solution based on other factors.