I use kindle. Have wifi turned off, and just load the books over usb using calibre. When you buy the kindle books off of amazon, you can download them to your c

I use kindle. Have wifi turned off, and just load the books over usb using calibre. When you buy the kindle books off of amazon, you can download them to your computer to then put them on the device, theres some DRM in there so only your devices will be able to read them. You still need to register the kindle with your account, but after that, it can be an offline device