For example, see here ?" He turned the faucet, disconnected the flask and handed it to Flint.
"There, sir," he remarked, "is a half-pint of pure liquid oxygen, drawn from the air in less than eight minutes, at a cost of perhaps two-tenths of a cent.

On a large scale the cost can be vastly reduced.

Are you satisfied, sir ?" Flint nodded, curtly.
"You'll do, Herzog," he replied--his very strongest form of commendation.

"You're not half bad, after all.

So this is liquid oxygen, eh?
Very cheap, and very cold ?" His eyes gleamed with joy at sight of the translucent potent stuff--the very stuff of life, its essence and prime principle, without which neither plant nor animal nor man can live--oxygen, mother of all life, sustainer of the world.
"Very cheap, yes, sir," answered the scientist.