They're plenty bright, but it doesn't show-up very well on video.
I removed the ones that came with my Interceptor sedan to clean the headlights, and put power across the strobe controller. They're on a par with the Whelen Vertex HAWs installed in the sides of the headlight assemblies. They seem to perform the function of providing a wig-wag without using the shutter-projector headlights well enough, but yeah, it's a lot of money for really basic wig-wag functionality. I think that's why most agencies don't buy the RftR options. I just happen to have purchased two decommissioned vehicles (one utility and one sedan) which happened to have those options.
I'd probably pay $75-100 each for them if I was to get a vehicle that didn't have them, I've seen a few on eBay for around that much.