I stopped using Amazon a while back, but it was where I got all my books for a long time. I do thriftbooks mostly now, and try to buy directly from publishers when it’s a newer book, but I’m always interested in finding new spots to cop some sweet books.
Google books used to work this way, but never tried it with Amazon.
That’s strange because I just did that with my kindle a few days ago with books from humblebundle. Only works with mobi file types though. Didn’t work with PDF or epub.
Glad you got it to work with calibre though.