Rationing in public health care

This article in the NYTimes was thought provoking - basically arguing that we are all in favor of rationing of health care unless we've got the cash to pay for everything ourselves.

This question illustrates the basic argument:
"Public Health Insurance should pay up to $__________ for a treatment that would extend a patient's life by 1 year."

Is the answer $10,000? $50,000, $100,000, $500,000, $1,000,000, $10,000,000, $100,000,000? .... I get the point. We already ration health care - there is a limit to what we spend on it - we just don't think about it explicitly. The question is how much value do we place on extending life?

An interesting corollary - it makes more sense to spend more on health care for younger people (who might live 40 yrs if they survive a crisis) than older people who are likely to have shorter expected life spans. (the same treatment extends the life of a younger person longer than the life of an older person).