I need an econ refresher

Dear all,

Would someone please explain to me how it is that the .mobi (ebook) version of a book costs around 13$ while the used paper copy costs 0.01$? Is this a case of supply-demand? Because then...how is the supply limited? It's digital. Making a copy of a digital book doesn't take that much resources or energy, even compared to the making of mass-market paperbacks (which still requires paper making and binding and such). Most authors these days have their final transcript in digital format, anyway, and it's not that hard to convert .doc to ebook formats. I've done that before too. There are even free online software for these sort of things.

Perhaps it's because the paper-copy is "used"? But...it's digital. I mean how do you even tell apart "used" from "new" copies? But if that were the case, where can I get used digital books? Because seriously, I don't mind used books. Either paper-copy or digitally.

This mini-rant is brought to you by my visit to the library website. I'm one of those people who prefer not to buy a book until I've read it and know that I like it. I read fast. To entertain me for extended length of time requires something either massive or going to the library (whose schedule overlaps with mine by only two hours every week) every week. I have a kindle. I have gone through the entire SD library ebooks collection. There're just over 2000 books. There are five that overlaps with my to-read list (121 books so far). They all have wait-lists ranging from 6 to 36 people. Hunting on the internet has not helped much.

Help.

[edit 11:00]
New thought: I hate to default to thinking the worse of everyone, but I realized that it's possible for it still be a supply-demand situation where, because the supplier knows the demand is high, they can purposefully limit the supply in order to charge higher prices and therefore obtain more profit (and they don't even have to subtract printing and distribution costs for ebooks).

Thoughts? 

Dude

I think I just found a new incentive for why I'll want to aspire for a job that pays well. Besides the hope of affording a house with a backyard large enough for me to grow things in, I mean. (I suppose I could move to the middle of nowhere if that is my sole incentive, but it does seem to conflict, logistically speaking, with finding a job that pays well in my particular field of interest.)

Look at it. Gaiman's library. Although that is not the level that I'm aiming at (I am, after all, very pragmatic). I do want to be able to have at least one extra bedroom and install it with wall to wall and floor to ceiling bookshelves. It's getting a bit tragic how often I wander past bookstores now and force myself only to sigh and cast a longing glance before moving on. Quickly. (I'm convinced I'd be lured away by its siren calls if I pause in front of it for more than three seconds.) Perhaps this is what lovesick adolescent girls feel like. There is, however, considerably less stalking and crisis over self-image in my case, so I feel that I've got the better deal.

Dude. Books.