I have only found like 3 online. all of them run in the 2k range. which seems excessive to me. They don't even shoot anything, well 2 of them shoot lasers, but I don't see that being helpfull without the even more expensive training system that uses it.
I did some research and if I feed the air through the existing barrel, I think I can build a system for around 100 bucks.
If I feed it through the mag well, I will need a new barrel, and it would probably run closer to 200. But that will depend on how cheap I can find a barrel to modify.
I guess the question is, does anyone care enough about automatically cycling the slide when dry firing that 200 bucks isn't too much to spend for practice.
It is close to the price of 22 conversion kits. but for those of us not able to get to ranges, it is more useful.