Well to get one idea you can take a look here:
Amazon Kindle Bestsellers
http://www.amazon.com/gp/bestsellers...d_i=1286228011
vs
Amazon Print Bestsellers
http://www.amazon.com/gp/bestsellers/books
The New York Times separates out ebooks in their bestseller lists too.
Looking at the Kindle list, there are a lot of books around $7.00 or under but I'm not sure how many of those are Agency 6 bargains and how many are indies. (Note that the "Bailey Flanagan" books were just discounted a few days ago, so that is why they are appearing there.)
But even if the cheap ones are indies, this doesn't really tell us if the big publishers are actually losing sales to indies, or just continuing to sell print books rather than ebooks.
eP