(Well, at least they used to--I have no idea if they still do.)
So whoever decided to not carry caffeinated Coke, Pepsi, or Mt. Dew gave the thumbs up for Antartica Guarana (which has more caffeine than the colas do, but it occurs naturally in the gurarana extra rather than as an added ingredient, so it doesn't show up in the list of ingredients). Good times.
Of course, gurarana is an acquired taste, so it may not be your cup of tea, so to speak.
The other source of caffeine there at the bookstore is Excedrin.