Grab a Wacom Intuos. They survive 5 years with ease, and it is easy to get spare parts like pencil tips or cover sheets.
Get one size larger than the largest you can afford.
The Large is preferable (A4 size). It works so much nicer than the A5 or smaller ones. I know it costs a shïtload of money, but it will seriously improve working speed and decrease RSI troubles.
As said before, if you are on budget, a second hand might be interesting. All models since the 3 are great.