THE CONSUMERIST has put together a chart that shows the cost of various liquids including HP ink.

One of the most interesting points on the graph is that it shows the cost of human blood at .39 cents a ml, while HP printer ink is more than double that price. It should also be noted that penicillin which has done more for humanity than printer ink costs less than 10 cents a ml and that crude oil is only a penny a ml.