Today I tested again the hack of a Logitech Attack 3 2-axis usb joystick, where I substituted the x-axis potentiometer with my own cheap 1 turn 100K linear taper potentiometer (300degrees max, manufactured by Philmore). I will probably upgrade the current potentiometer to a precision industrial single turn potentiometer, once the prototype is fully tested - it will last longer, smoother, have a better linearity. The Vishay Spectrol Model 157 for about US $20, datasheet http://www.vishay.com/docs/57042/157.pdf has good review and would be a good choice.