e-reading

I got an e-reader for Christmas and have been happily trying it out. I've been reading both public domain texts (free is always nice) and more mainstream texts. I've been loving it. It's just the right size to hold, and I actually really like the dictionary feature since I don't have to read with another device near me if I want to look something up. (I've been known to take my smartphone out with me when I'm reading a novel, just in case I want to look something up...)

But the one thing that surprises me is the cost of ebooks. I was compiling a list of books I'd love to read this year (a short one, thankfully! - these lists aren't always so) and two of them would cost more as ebooks than as paper versions. And since I always buy enough to get the free shipping, why would I want to pay more for an ephemeral ecopy? This I do not understand. Can anyone explain?