As Veektohr said there are a few people who do production runs of these that I have seen.
Here's some pictures of my saber with the clip that I got from Sni9er, to show you how they're supposed to work. Ignore the unpainted belt piece
To start with, here's the piece that sits on the saber next to the clip itself. Note the notch in the belt piece as well as the extruded piece on the saber section.
The gold piece slides inside the belt piece. The extruded bit on the saber side will eventually meet the edge of the channel and provide some reistance as it slides through.
As it slides down the extruded piece meets the notch and kind of 'locks' into place here.
In this position (in fact, even with the friction alone inside the channel) the saber hangs quite safely in place.
To remove it you pull the saber down and out the bottom of the clip.
I can't comment on other people's products but the metal one Sni9er was offering (not sure if he still is) is excellent in quality and functionality.