One of the most cost effective performance supplements in the world is creatine monohydrate. While naturally found in meat and fish, the amount is very small. Widely used by body builder and athletes, creatine significantly increases power output, muscle size and overall strength.
The best way to consume this supplement is to load it initially, by consuming 4 x 5g serves every day for 14 days. Your muscles will then be sufficiently saturated. After this, consume 1-2 x 5g maintenance dosages per day.
Pure pharmaceutical grade creatine monohydrate.