Fred, publisher of the excellent science fiction zine Kaleidotrope, recently posted on his personal blog about the morality or immorality of buying used books. He says:
The right of resale has existed for a very long time, even before the internet came along to make the process quicker and easier. I buy the argument that the internet has changed bookselling and publishing, often drastically cutting into profits [ ... ] But buying used books is not the problem. It may very well be a symptom of a larger problem — why are more people buying used books instead of new? — but it's the larger problem that ought to be fixed. [ Bad Book Buying? ]
There are heated arguments on both sides. I have an opinion, too, that's beside the point. In the meantime people are selling used books and you have to respond constructively to that behavior or let it roll over the top of you.
There's a wealth of data here for media publishers and writers in the relationship of the used media price to the new media price as well as the availability of used copies.
For example, as of this writing Amazon lists 323 used copies of the Sam Rami Spiderman movie, with prices starting at $0.30. What's that suggest? The popularity of the movie has foundered. Lots of copies were made and lots of people bought copies. But no one wants to devote shelf space to it any more.
On the other hand, there's the long out-of-print Muppet Movie soundtrack. There are eight used copies on Amazon with prices ranging from $95 to $120. There's pent-up demand here, and the people who own this CD tend to be keeping it.
Smart media producers and publishers could take this information and see how people feel about the products and what people want better than ever before. They could evaluate niche markets. See what products are ripe for re-issue. Watch the pattern of fad-purchases and try to adjust production and stock levels in expectation of used-media gluts.
Often, when we find what we've created is not being used in the manner in which we've intended, our first response seems to be to find ways to force people into compliance with our processes. But it's worth it to resist that urge. How people misuse what you produce can tell you a lot about what they want from you that they are not getting.
You can get on your moral soapbox and preach about how people aren't treating you right or aren't showing your labor the proper respect. Or you can try to figure out what it is that you're not providing customers and find a way to satisfy those needs yourself. One strategy alienates customers and might entrench undesirable behavior. The other strategy brings you closer to your customers and might even make you more money.
In the long run, only one of those strategies is constructive.