A new service launching in October from Amazon will allow you to get free or discounted ebook copies of physical copies you’ve already bought from Amazon. It is called Kindle MatchBook and will allow you to buy the kindle edition of a print book you bought either for $2.99, $1.99, $0.99, or free.
There is a huge catch, though. It is entirely optional/opt-in for the publisher and they set the price. So you are still at the mercy of the publishers to make this a good deal (the same ones who colluded with Apple to jack the prices up). However, the prices should still be cheaper for the ebook copies, and I suspect a lot of independent authors will take advantage of the service and do it right.