It is like a brochure which can be distributed to people who come to the fair/bookstore/conference. It looks like the actual e-reader, but it's made out of paper. Inside pages have the best seller or very popular book cover on one side of the pages. (It could be lots of book covers per book cover page.) The other side of the pages will be promotional messages for e-books, including facts about e-books.
What is the core principle of your idea?
Making this item with paper would make the paper book readers right at home and it will make it easier for them to imagine how small e-readers are. Having the book cover pages inside will help them imagine how many books they can actually hold in one e-book. Of course the promotional message pages need to assist their imagination by stating like, "...and you can have 30,000 books on one e-book if you like." Book cover pages will let them think of what multiple books they want to read.
Can your idea be applied to different formats (in a bookstore, at a trade fair, at a conference)?
Yes it can be applied to different formats/venues.
Would it be possible to turn your idea into a reality, or at least create a prototype of it, at short notice, i.e. by the Frankfurt Book Fair in October 2014?
Yes, it is possible.
What do you estimate the costs for the prototype or the final implementation of your idea to be?
It will all depend on how many of them you would like to make. It will be nice to be able to hand out to people who come to the venues (bookstore/conference/fair).