Helium tanks are available from industrial suppliers, party balloon companies and online retailers. For example, Praxair in the United States sells helium in a range of purities to suit different applications. BallroomBalloons.com sells and rents helium tanks in size that include "baby," "small," "medium," "large" and "extra-large."
Helium tanks can hold liquid or gas helium and must be stored appropriately to prevent sublimation. Most of the cost is associated with the highly-specialized containers, not the helium, itself. A small amount of helium gas sublimates into more gas as the temperature rises, which can cause the tank to explode if it does not meet design specifications.