Smaller width is clearly impossible. Smaller cost, though... I wouldn't be that surprised.

These two pistons on track seem expensive, but an arm on track or piston without track just has so much less power, so I couldn't find a way to save money like that.
Unification needs so many access points, and with the width restriction as well, as well as the sliding motions necessary for input and output, it feels implausible to do this more cheaply.