You can get a Windows Tablet for what you want and you can use it with anything you want.
A couple of us have had good luck with the Microcenter Tablets. They have a 7" tablet for well under $100 and the 8" goes onsale for $100 at times. Worth a look atleast. I have the 8" tablet and it is pretty nice especially for what I paid for it.
Has a standard USB port for connecting normal USB stuff and has a seperate mini USB for charging purposes. mine also has a mini-HDMI if you wanted to hook an external monitor to it at a later time. The 4 core Atom processor is pretty snappy for what it can do.