You can get tablets for most price ranges - even reconditioned ones at places like CEX - in most cases you can get a keyboard of some sort fairly cheaply that will plug in if necessary. Android, the operating system on most tablets, is a version of linux which means there's a lot of free software about. The main point against such tablets is that they have very little internal storage (4-8 GB usually) and not much more by way of plug-in space.