Kent notes an article in Parade Magazine titled, "Debating the Cost of Capital Punishment." I say it's an "article" mostly out of charity, because it's actually a short anti-death penalty essay, with a paragraph representing the opposing side thrown in at the end.
One way to attack X is to write a piece called, "Is X Worth the Price We're Paying?" The price of policy X is surely worth debating, but to focus solely on its price, without examining its benefits, or the alternatives, or the price of those alternatives, is cheap and dishonest.
The cost of the death penalty is all the rage with abolitionists these days, but it's a make-weight, nothing more. It's designed to sell the abolitionist agenda without having to defend it on its merits -- something abolitionists shrewdly decline to do, since they know that the public supports capital punishment by 2-1, as it has for years.
I tested this proposition on Sentencing Law and Policy by making the following offer: I said to those pushing the cost argument that I would support reducing the use of capital punishment during the recession if they would support increasing its use when prosperity returned. You will not be surprised to learn that the number of people who took me up on this was zero.
It's not about cost. That is a diversion. The more telling question about the supposed virtues of "cheaper" life imprisonment is the one Kent asked: "Would you have Timothy McVeigh grinning at you from his jail cell his entire life the way Charles Manson has?"