Recently I was talking to somebody in the digital production department of a major publisher who pointed out to me that making an ebook from a print book is not simply a matter of taking the same file that the production department uses and hitting "save as" in a different format.
It's true the ebook folks get the book when it's "publication ready" -- the editor's read the submission, revisions have been made, the book's been line edited and is considered "good to go" for printing.
But that's just where the ebook work starts.
The text has to be converted, and no, it's not simple. It requires coding. That takes time and money, whether it's done in-house or contracted out.
When the converted text is finished, it has to be proof-read, checked and tested by the publishing house and errors corrected. As somebody who does her own website, I can tell you this can be time-consuming. It can be difficult to find a simple error that has nevertheless totally messed up the page.
If there are extra links involved, this means finding the material to link to, including the new code in the text, and more proof-reading and testing.
In addition to these costs you have the cost of hosting, testing the site at large and updating.
There are also costs for advertising and promotion online.
In other words, it's a lot more labor-intensive and costly to produce an ebook than one might think.
That said, I don't think an ebook should be more expensive than print, but now I can understand why it would cost the same.