You can get neotame online, including on Amazon. I really dislike it though. Its sweetness has a very strange attack and decay, if that makes sense, so that there isn’t really a right amount to use where it won’t taste some combination of too sweet and not sweet enough over the course of a bite or sip.

Neotame is cool stuff, I bought a packet online and it's wild. Ultimately, I went back to stevia which is fine for my purposes.