Does anybody have recommendations for a drink carbonator? (like a sodastream)

My partner likes fizzy drinks. I want to get something that will last, and won’t lock us into a single vendor for refills or replacement parts.

I looked at making our own custom one - like this. We might still do something like this, but I’m also pretty clueless with this stuff and don’t want anything to explode or poison us :)

Our priorities, ordered by importance, are:

• No lock-in (adversarial interop is fine)
• Well built/long-lasting
• Convenient, safe, easy to use

Any suggestions?