I chopped my aerobars on my own with a hacksaw and a saw guide (they made for cutting steer tubes, but will clamp to anything round). Mine are carbon- the one thing you have to watch out for is the dust- try not to inhale it or get alot on you, because it gets itchy.

I used trial & error to get the length right- it took cutting them 3 times, because I didn't want to go too short.