A quite complete German seller is
He also has most of theSparkFun products at reasonable prices.
Motors - i.e. generally "servos" - are best bought through eBay, but you might also find something not always very expensive here:
http://www.conrad.de/ce/de/suggest/servo
A 20 Euro standard Arduino 328 should suffice.
If you want to miniaturize it a little bit than have a look at smaller sized boards... Linux connects fine through USB
Servos can easily be directly connected to any microcontroller, however you will need external higher 5 volts current (around 2 amperes?)