There are lots of other sites that have current ebooks. Google .. . plus you can take them out at your local library.
There are sites out there and @ a lower price than Amazon.
You can use any extention and convert , i.e. if you download a .lit book you can convert it to any another extension using “Calibre” , a free converter (it’s great and easy.
Here’s one link for a site and there are plenty more. I don’t use Amazon at all.