Can't answer your question about glockworkx cost, but before I got the DAA race master I had an uncle mikes and it fit fine. Not as fast as the DAA, but with practice it can be close.
That being said, a Jager kit is about $550, plus your trigger and it can all be put together in about an hour. Red dot not melded in though...
+1 on taylors +8 extension...that is the way to go there.
Good luck.