Caveat emptor!
First off, you can probably get these bags even cheaper by buying through eBay, you seem them listed as Dynatran all the time. I picked up a holster bag for the princely sum of 25 cents. Not dollars, but cents. Plus shipping, of course, but still, it was well under $10 total.
Second - my plan was to try using a holster bag on my belt. After all of two days of use, it ripped off my belt, sending my camera crashing to the ground. And this with a fairly light DSLR and light kit lens! Fortunately no damage was done, but upon closer inspection, the belt loop was
woefully weak, especially when compared to the belt loops on holsters from Tamrac, etc. You definitely are not getting Tamrac quality for the price. In my case, it was so cheap that it wasn't even worth sending it back, especially when the replacement will still have a pathetically weak belt loop that I wouldn't use.
That being said, you can probably do OK if you keep your expectations fairly low. Now that my K100D is basically "the wife's camera" (complete with red Op/Tech strap

), and she is not going to be changing lenses very often, we use the cheap Amvona holster bag to protect the camera, and support it via the camera's strap, which sticks out the sides.