I have found Ginseng (which can be found at most large asian markets in small vials of 6 year old red panax Ginseng) to be far more effective than coffee at clearing the mind. Increased alertness, faster thinking and minimal side effects. You shouldn't pay more than $3 for 10 doses, although I've found that a large grocery store will sometimes carry 30 doses for $3-5. Ginseng is not Jittery like coffee but you could always combine them for marathon levels of hyperactivity.