Yeah I have the Rheobus, it's an awesome controller. Have it controlling all my fans, like 10 total.
I wasn't 100% about controlling a cold cathode only because I hadn't really read into it before. Of course it seemed possible, but whether it was safe to do was my concern.
Anyway, yeah it cost me like $20-$25 US when I bought it, but it may be more expensive being in the UK