Amazon’s prices on books that can be discounted (and don’t belong to the “agency model” of the big Six), are generally less expensive.
A former sampling of pricing between Kindle and iBooks for the New York Times Bestsellers revealed:
80% of the books were the same price on each platform. And the 20% that are cheaper on Kindle were cheaper by an average of 11% or more.
If you want to shop around, a free tool like Inkmesh.com can save you a lot of time. The benefit of inkmesh is, that even if the prices listed may be different from time to time, it compiles all the links in one place, making it easy for a reader to compare the prices before purchasing. Most e-book prices are pretty similar from retailer to retailer but not all retailers have all those e-books available.
There are also many classic books for free ( I read somewhere over 16,000 and counting to download) because their copyrights have expired. And the number of free books increases from year to year as more and more copyrights expire and go public.
Free books are also offered daily by Amazon. Even when you choose very carefully among these e-books and download only the best, you will have a whole library in no time. You don’t need to own a Kindle, just a free Kindle app and the e-book goes to any device.
And then there are the e-books that you can lent at your local library – or at Amazon, if you have a Prime membership. This is even a good deal for authors as well as they will receive an average of $1.70 for their book if it is lent by a Prime member, no matter what the retail price is: 99cents or $9.99, this way making more money with “unsold” books.