My Windows 2003 Server training kit went for about a quarter of its original value on eBay, which accentuates one reason why I got out of IT. The question of who will even care about this stuff in five years is clear when you try to re-sell your computer books. Microsoft especially has a training treadmill in which your free time is driven by their release cycle. It becomes tedious, which is why many IT professionals stop caring about things like certifications, although the knowledge of these new systems is not something you can ignore. Those who know their stuff make the big bucks. Management is a good refuge from the treadmill too.
In contrast to my IT books, I took some of my Buddhist studies books off the shelf and considered selling those too. Let's ignore the fact for a moment that I'm considering selling Buddhist texts to support my Warhammer habit, Forge World specifically; that's too messed up for this early in the morning. What I found was that some of those books, that I desperately scrounged to acquire as a grad student, are now worth a small fortune.
Twenty-five year old Zen translations from Japan are the hottest, with several worth over $250. Some are simply unavailable anywhere. These books were hard to get back then, and it was only because everyone knew it was my area of study that they became available to me. They're the equivalent of first edition, first printing, unpunched classic war games, for the gamers out there. It's true that a career in Buddhist Studies would have been a long, expensive, and not very lucrative process, but you can't deny that five years later, or even twenty-five, people care about these things. The disconnect between what's truly of value or what truly brings happiness and a lucrative career is nothing new of course. Ask an English major.