what to buy??

hello everyone. I recently got my arduino and I have been playing around with it with leds, potentiometers and a servo I have. I want to get more things to play around with. like sensors etc.

I have $75 I can use to buy things. What should I buy?? I was thinking of getting some motors, high geared motors, some rgb leds and a piezo vibration sensor. maybe even a wii controller, since I noticed its cheaper to buy a wii controller than an accelerometer.

another question what is the difference between a regular dc motor and a stepper motor?

If you apply voltage to a normal motor it just spins. To a stepper motor you apply voltage to particular coils in the corect order and the motor axle moves a defined angle. Whit a stepper you can pretty accuratly define where you want to move something to (matrix printers used this to position the printing head).

another question what is the difference between a regular dc motor and a stepper motor?

See this:-
http://www.thebox.myzen.co.uk/Workshop/Motors_3.html