Robart bought out
CompactUniBrake a while back. These were brakes that were sized to fit Robart wheels and were under $100.00 for the setup. They were based upon the BVM style and, I think, were liscensed by Violett to be made by this company. Worked great on all the jets I have, up to twentyfive pounds. (Don't have any heavier than that.)
Hopefully Robart will have them back on the market soon, as I have seen ads for them by Robart in the model mags.
Hobby Lobby stocks the Kavan electric brake which works great on a trike nosewheel.
http://www.hobby-lobby.com/wheels.htm#Brake