An underdrive pulley costs 40 euro's and a fidanza flywheel a little over 200 euro's. With taxes and shipping the 2 will be somewhere around 350 euro's.
@Marc: There's a difference between hp at the crank and hp at the wheels. a pulley and flywheel obviously do not improve your engines hp, but they do improve the amount of hp that eventually reaches the wheels. In combination with lightweight rims (like the OZ's Outlaw mentioned) and lightweight lugnuts it's a significant difference.