I have been experimenting with odd less expensive belt keepers and holster enhancements for over a year, and noticed I had a bunch of laptop straps, and the straps have various types of shoulder protection, these various protectors can serve as keepers, and retain the end of a long belt to stop it from hanging loose, and also used to retain a loose holster from moving around on your belt, I use a leather belt not on the pants loops and the right combination of parts makes my holster very solid in the position I need it to keep.

Laptop straps are very cheap, even free, at thrift stores etc, you need to look through bunches in order to cobble up what you need, however I find the flat plastic ones best for keepers and general use, durable too, so far stuff has cracked, but not all the way and stood up to the abuse of biking etc, cheap and good.