There is much fun that can be had with these launchers.
Alas, little of it when they're actually attached to an AR.
As a FLARE LAUNCHER, they are not even a firearm.
I've got a small supply of cases for mine, and while I've got it lent out to a friend for the winter, I've had a bunch of fun with it.
There was a recepie for using 85mm aluminium cases, with some FFF black powder, and empty black/grey lid film cannisters. I found that to work quite well. Some roofer's chalk, a few washers in the cannister for weight, and they'd go out to about 150 meters with the right load.
As a stand-alone, I used it more often, as it was a bit of a pain to run on an AR.
I built my own stand-alone mount for it, and the photos of the various aspects of construction can be found here:
http://www3.ns.sympatico.ca/coffee/pics/Project/
The project was not expensive material-wise, but I seem to recall it taking a considerable amount of patience/machine-time in my shop.
If I was to make another for someone else, (not offering) it would probably be in the $400+ range for the stand-alone system.
NS
....easy to obtain 
, less so....
