Robarts Electric Retracts #ROBQ1649 - $649.95
Robarts Pnuematic Retracts #ROBQ1 - $469.99
Sierra 1/6 Scale Pnuematic Retracts #1/6 Zero Mains - $480 (for Yellow Models)
Sierra 1/5 Scale Pnuematic Retracts #1/5 Zero Mains - $570 (for Ziroli Models)
Not sure where Sierra retracts are cheaper; unless I'm quoting the wrong Sierra Retracts?
The Sierra Pnuematic Retracts are cheaper than the Robart Electric Retracts, but so are the Robarts Pnuematic Retracts.