Pretty much what dman811 said, get a usb Wacom tablet to draw on. Trying to draw on a capacitive touch screen tablet is going to be a nightmare. Your results aren't going to be very good because you have to use a big fat tablet pen
. It's a reason many artists do not choose to draw on capacitive touchscreen tablets because it lacks fine controls.
I'm not even sure if you can get a full Photoshop software to run on Android tablets. Your cheapest tablet would be an actual Wacom tablet
. Your next best bet is to get a 2nd hand used tablet pc convertible off eBay. I have a Fujitsu T5010, those can be had for around $200 if you don't want a Wacom tablet. And if you want something new the Microsoft Surface + ArtRage combo is popular among professional artists. The Surface costs around $800-900. Stepping up from that I would recommend Lenovo X230T around $1,000.
Capacitive touch tablets are really a terrible choice to draw on. I would recommend saving the $$$$ and not bother with capacitive touchscreen drawing. I drew once on capacitive touchscreen PC, it was so awful that I returned it. But if you really must have something portable I would still recommend a used Tablet PC Convertible over a really bad capacitive touchscreen for drawing.