Why is pornography scarce?

"Playboy Archives Go Digital," so read The Wall Street Journal headline from last week.  That’s right, 636 issues, on six discs, $100 per disc.

Have you noticed that storage is really, really cheap these days?  Have you studied the durable goods monopoly problem?  Once you’ve accumulated a stock of durable material, at some point you will sell off successive units very very cheaply.  Have you noticed that costs of electronic reproduction — call it marginal cost — are really, really low these days?  Have you noticed there is a massive stock of accumulated pornographic images?

Hmm…try graphing that equilibrium.

Call me clueless, as I have very little direct knowledge of pornography.  But I don’t understand why buyers demand such a regular flow of material.  Why don’t they just buy a single dense disc of images and keep themselves, um…busy…for many years?  I believe also that fetishes are fairly stable and predictable.  You don’t need to see "the new porn" to know what you will want to get off on.

As I observe the sector, buyers cough up new money all the time, and they buy relatively small units of output, and at relatively high prices.

Please "splain" it to me, as they say…

One possibility is the neuroeconomics explanation that buying the material yields more pleasure than "using" it.  Maybe porn and cookbooks have something in common after all.