That which is not 'for sale'

There are many possible examples of grading exchangeable and nonexchangeable goods on one’s value scale. Suppose that a man owns a piece of land containing an historic monument, which he prizes on aesthetic grounds. Suppose also that he has an offer for sale of the property for a certain sum of money, knowing that the purchaser intends to destroy the monument and use it for other purposes. To decide whether or not to sell the property, he must weigh the value to him of keeping the monument in­tact as against the value to him of the consumers’ goods that he could eventually buy with the money. Which will take precedence depends on the constitution of the individual’s value scale at that particular time. But it is evident that a greater abundance of consumers’ goods already at his disposal will tend to raise the value of the (unexchangeable) aesthetic good to him as compared with the given sum of money. Contrary, therefore, to the com­mon accusation that the establishment of a money economy tends to lead men to slight the importance of nonexchangeable goods, the effect is precisely the reverse. A destitute person is far less likely to prefer the nonexchangeable to the exchangeable than one whose “standard of living” in terms of the latter is high.

..says Rothbard in Man, Economy and State (chapter 3). And how true! Who cared about things of beauty or historical significance when everyone was poor? It is only when the people become rich that they can afford to preserve, protect and preserve things of beauty and historical significance (as judged by someone). So do you want preserve the wildlife in Africa or the Buddha-statues in the Middle-East? Then preach capitalism for those regions!

Market failure or lack of understanding?

Once one chases down the rabbit trails of "utility maximization" and the esoteric notions of "market failure," it is doubtful that one is going to understand simple opportunity cost.

Exactly! More on this here: Krugman's Straw-Man Market System. Do you want to learn about economics? Then don't study economics in school.