Yeah, they are often expensive, but I found an open box sale bt keyboard, and it works great. Mice are really cool to use in Android, too. For a while I did everything with my tablet. My first tablet was the Acer Iconia A500 and these have a usb port; keyboards have been working on Android since at least Honeycomb.

When using a physical keyboard on Android, Ctrl-Z, Ctrl-C, etc. work as expected with text.

With my tablet, I can connect to my PC from anywhere and work on it as if I were sitting in front of it. This way I don’t need expensive hardware like a top of the line graphics card, sound card, etc because it’s all done through my tablet.