This 28BYJ-48 stepper motor is perfect for projects that require precise motor control, and is well suited for small scale robots.
The unipolar 4-phase 5 wire stepper motor drives a gearbox, which then drives an output shaft. The module includes a ULN2003 motor driver chip.
The output shaft takes 4076 motor steps per revolution, and we have seen it run over 25RPM at 12VDC.
Although we do not recommend powering anything from an Arduino, these do run on 5V, meaning you could control this from a Uno or Mega without additional power supplies (without a load) using the 5V and GND pins.