Certain people are nagging me to get one so I can read my PDFs on the train. Its a good idea, despite my reluctance to get involved in new tech. But which one? I was reccomended an Amazon fire 8 inch. Kind of middle of the road. What do you think? I dont need a fancy one. You see the 16gb cheap...but can you get add on memory or change to a 32gb? And how do you transfer PDFs to the device?