I cant do the ones that fit between the belt and body. Just not me. The one I'm talking about is called the Texas Yaqui Slide and only cost $40.00.
http://www.kirkpatrickleather.com/product/h_tys.htm
I was thinking the same idea about using an exacto knife and cutting the circle like Galco does on the back of theirs to allow for the holster to set over a belt loop.