That seems to be in line with what I thought most ebooks should cost: $3-$5. $10 is still too much for the digital world, and it's a lot of the times even more expensive than paperbacks. Considering that after you recover your initial investment, it costs virtually nothing to create and distribute another copy of the book (unlike with paper books, where every extra copy has costs tied to it), that makes no sense to me.
Plus, selling for a lower price could get authors more money, too. I believe it was on Techdirt where I saw how a $2 book brought twice as much money than the same book sold for $10.