Hi and welcome. The price surge you see on e-books has a lot to do with the Agency 5 model where the book stores are no longer allowed to decide the price which is set by the publisher and must be adhered to by everyone who wants to sell the book.
Big established authors will be hard to find elsewhere for a lower price. There are however alternatives if your willing to go with non established authors.
Smashwords (all sort of books) and
Baen (Fiction) are two stores that comes to mind.
If your willing to read old books where the copyright has expired there's a
ton of books here at Mobileread which won't cost you a penny, except a thanks to the up-loader.