You can buy them from Murph's, who is an excellent vendor. You can also do a general search if shopping by price.
One thing I would caution you about though: there are two different types of switch from and for the Rostra: one uses klixon switches the other uses conductive buttons and a PC board. The klixon switches will corrode and fail. The PC type can be covered in grease and will last for many years, the klixon switches have not lasted over about 1 1/2 years for me although I do ride in the rain as required (on trips, rallys, riding IBA events, etc.). I always suggest buying a switch that has an 'engaged' light, and it might be worth a call to Rostra to find out what switches are of which type before buying the unit, and then get the actual CC either with the switch you want, or buy it without any switch and buy the one you want separately.
Brian
Horizons are enroute. Is any one source for a Rosta cruise better than others or is it simply search the web for the best deal? I'm not concerned about the actual installation of the Rosta unit, it's really more about making the time to do it. One thing leads to another and the next thing I know my bike has been apart for months. It's not that it needs that much work, in my world, whatever come up is more pressing than what I'm currently doing.
Never had a problem with the Cramp Busters, like I mentioned previously, I've used them for years.