In a capitalist economy, all things being equal, rare items will cost more than common items. There is also, in a capitalist economy, something of a tendency to confuse price with value. They are interchangeable enough on mass produced items, but when it comes to priceless items the connection breaks down entirely (I'm using the term priceless somewhat loosely).
For example, air is free and yet extremely valuable. On the other end of the spectrum, though very costly, a celebrity endorsement by Saddam Hussein for the nissan sentra would be utterly worthless.
There is something of the same phenomena that goes on with art. A full-sized print of the Mona Lisa would look just as good as the original, but its price would be completely incomparable. A more stark contrast is offered by photographic art, as there a print would necessarily be identical to the original piece.
I think that nearly everything in a museum suffers from this phenomenon. A bowl that is of small consequence to the person who fashioned it becomes of extraordinary value if it passes (typically buried in dirt) through a few millennia. Naturally such a thing would be very expensive, because it is very rare, but its price distorts the perception of its value. If one honestly looks at such a bowl, it's not useful for any practical value, it has no lessons to impart once we've figured out how it was made, and it's not pretty.
It's telling when one of the museum staff of the Baghdad antiquities museum said that knowledge of which are the valuable pieces indicates that the people who took them were educated, for to the uneducated they just look like rocks. They are rocks. Once we have photographs and a translation of anything written on them, they have no more value than rocks. Yet they cost much more.
Don't get me wrong. I'm an ancient-phile. To me Socrates is nearly living, and I have great sympathy for the feelings and thoughts of that much rougher time. I find the classical taoists of China quite intruiging, especially Chung-tse. Which is part of the reason why I can nearly hear their laughter at the modern habit of worshiping worthless items merely because they're old and rare.
This is very odd for me to say, because I am one of the proponents of Culture!. I love classical music and I think that Shakespeare wrote some of the best English sentences ever written. I think that Socratic philosophy should be mandatory study in high schools. I wish that more Christians would read the gospels cover to cover (they're short!). I deeply revere the old world and the ancient world.
Yet I think that some element of practicality is needed in judging value. As much as it is a pity to lose things which are rare, in the case of antiquities which we have photographic copies of or 3D replicas of, what is lost if the original clay tablet is destroyed? What benefit does the original give to people that the replica does not? Whose life is improved by the length of time that the clay was dry?
A man is worth more than many sparrows, and a sparrow more than many hunks of clay. It is easy to think books, antiquities -- anything that we are fond of -- are sacred and valuable beyond words. Yet there is a warning in this: it is not a virtue to put more value in something that it is worth, for that is the essence of all sin. Pride, envy, gluttony, sloth, wrath, avarice, and lust are all a matter of amplifying the value of a thing far beyond its true value. There is, of course, the opposite sin of undervaluing something. (Allowing a poor man to starve to death is a good example of this.) But perhaps the next time one is inclined to snort and think ill of the uneducated masses who have no appreciation for the cultural treasures in a museum, it might be worth considering that they could well be right. When you get down to it, all rocks are old.