I picked out a part list to make it a real tablet (if you could find similar parts for cheaper reply with links to them (no ebay))
Battery https://www.adafruit.com/product/353
Battery charger https://www.adafruit.com/product/2465
Speakers https://www.amazon.com/dp/B01JS6QHWQ
Display https://www.amazon.com/dp/B01IH6ZWWO
Raspberry Pi https://www.amazon.com/dp/B01C6FFNY4
And Cellular NeeCoo Bluetooth V4.0 Dual SIM Card Adapter-29.99 Online Shopping| GearBest.com