It is possible to nicely control the speed of a control system with a switch type joy stick if you use it as a relative control with timing. Have the switch closure initiate a change in present speed and increase the amount of change per unit time for when the switch is closed for a longer period of time. When the switch opens have it either leave speed where it is or have the MCU ramp the speed back down to zero.

Linear type joysticks that control speed relative to position of the control may be suitable to certain applications if the only time you want the control system to run is when you hold the stick away from its center NULL position.

For linear type take a specific look at the types of controls used in the robotics area used to control R/C servos. That may be your lowest cost alternative.

Michael Karas