I have picked up Fusion Reactors for over a dozen of my figures; some still going strong after a couple years of on/off. It can sometimes be tricky hiding the wires, but activating my entire collection with a remote control is a joy that still puts a smile on my face.
I got a large amount of my FRs ordered during their Black Friday sale a few years back and picked them up ala carte as the releases trickled in. While potentially pricy with large orders, they know the figures well and give just the right amount of wiring for each one.