Δυο καλές απαντήσεις από το  Wired:

• Τεχνολογία

Tacking an e onto a book requires antipiracy software, digital warehousing, extra legal support, and programmers to adapt each title for Android, iPhone, Kindle, and all the other formats. That’s on top of the regular costs of turning a manuscript into a finished product.

• Ψυχολογία

Publishers do price ebooks a little higher than necessary, because they’re concerned about devaluing people’s perception of books

Ολόκληρο το άρθρο: Burning Question: Why Do Ebooks Cost So Much? | Magazine.