I want to make my own DJ-program and controller. I have made one in Max/MSP before and thought I'd try PD (Pure Data) this time. I think I can manage that, but the controller will be harder. I want to make it as much from scratch as I can, using homemade sensors and sensor-interfaces from gamepads or something like that. I want them to use OSC to communicate with PD. For starters I want to have buttons (cue/play), sliders (the speed/pitch of the song) and something that rotates without start- or stop-points (also speed/pitch of sound (when spinning this forward the speed goes up, when spinning it backward the speed goes down), adjusting cue-points, and, maybe later, scratching). I know that homemade sensors are unstable and deteriorate with time, but hope I can learn more about this and maybe find information about materials that don't deteriorate as much or how to make them not deteriorate. Can someone point me in the right direction here? Maybe to a better forum for these types of things? Or to some kind of tutorial or guide? I have searched the internet and this forum, without finding anything.
If I can't use homemade sensors, I wonder where I can find the types of sensors I need and maybe if it would be better to use Phidgets or Arduino or something like that. And in that case – what things like that? Can I just buy slider/fader from some kind of electronics-store and connect it to a sensor-interface I made from a gamepad? Do I need to calibrate something? How do I find information about these things? Can you recommend specific sensors or stores?
The goal is to spend as little money as possible, but it has to be possible for me to be able to build this within “reasonable” time and without spending much time practicing and reading.

Thank you!