What's the cheapest gadget that can read pdf's and that i can also use to write?

I need a little gadget that i can do two basic things with:
-Read .pdf's
-Be able to write documents

That's all i need from it. Don't say 'iphone' or 'any smartphone', i'm really looking for a cheap solution to a simple request, i don't want anything fancy.
By write i mean keys/touchscreen with letters. Not stylus writing.
I don't want to edit PDFs specifically. I just want the device to be capable of writing into say a Word Document or a .txt.