I made my own glue-in plug for about $1. All it takes is an M5 or M6 thread insert from Ace and some epoxy putty. The plug only needs to be about 2cm long, not even close to the full 4cm length of the typical steering tube clamp. Complete with bolt and top cap, mined weighed 17 grams compared to 45 for the FSA compression plug it replaced. The plug alone weighs about 8 grams. Here's a pic of the plug showing the bottom side.
