See above. It's not required to use the Notecard, but it's extremely easy to use and convenient. The combination of the Notecard and the Notehub are essentially a simple JSON-centric "data pump", with a good deal of carrier data included.

We've priced it so we can make an "infrastructure-appropriate" profit on a sustainable basis; there's no 'surprise' business model and your data and your devices are yours, not ours.

same here - "Prototype" ($0/mon) looks like what most hobbyists would use who exceed 5K/mon:

https://blues.io/services/