A packet of this. 16oz of water or so, shot or three of vodka. 120mg of caffeine and a bit of B12. I don't care that the back of the box looks like a tampon commercial. 3bucks a box at wal-mart, so about 30c per packet.
I use these for my caffeine fix.
About $3 for a 10-pack at wal-mart, and 120mg of caffeine each. I could probably do better with instant coffee or just... coffee, but I'm saving quite a bit over my old habit of daily energy drink.
30cents or less for a dose of caffeine half way between a Red Bull(80mg) and a Rockstar(160mg) is pretty decent. I throw one in my insulated aluminum water bottle and fill with ice water and I'm good to go.