Try going to
www.inkmesh.com to price shop for books. A search there will look through many of the different bookstores. There are a bunch of independent stores and Sonys are not tied in to the Sony store. The Sony will read ePubs from anyplace except B&N and Apple. Library books are a fantastic resource for free reading.
I've never quite figured out why people are so set on WiFi or 3G. All of the reviewers who make that out as a crippling distinction probably contribute. My Sony will hold well over a 1,000 books; I doubt that I'll ever be anywhere with a need to buy a book right now and nothing else to read. Calibre does a great job of organizing my books and putting them where I want them, so sideloading with Calibre works better than loading with WiFi.