I use a Logitech Extreme 3D Pro, which I bought specifically to play KSP, and I've got to say that its awesome. It wasn't particularly expensive, but the build quality (to me) seems really good. The stick itself has 3-axes, which I use for pitch, yaw and roll. I use the trigger for stage seperation/ignition. I use the thumb button for MECO. The hat switch is awesome for RCS translation up, down, left and right, and I use the buttons next to the hat switch for RCS forwards and back, as well as SAS and RCS toggle. The throttle is pretty self explanatory, and the rest of the buttons are used for an assortment of things like opening the map view, deploying landing gear, and time accelleration. I tried playing KSP without the joystick the other day, and found it really really difficult!
