I used to get it from a place in India, and way way waaaay cheaper than anywhere else I've seen, but that place is gone too. Was great stuff for working the night shift
It's great if you need to stay up late. In me, it doesn't feel like a typical stimulant in that my energy level doesn't go parabolic. Instead, I remain at a flat, normal, daytime energy and alertness level throughout the night, instead of getting tired.