theoretically, if you can blag the sensors out of a wii controller, and a arduino pro mini copy, you have a very cheap IMU to start working with,
google multiwii,
but in practice its going to get pricey quickly, you can buy a cheapo walkera cuad for about 50 euros, or you can even look up how to take the motor out of a cd drive and use those for cuads, since the motors and ESC´s are the most pricey part of a cheap cuad that might be a good option