Where can I get one for a decent price?  TIA

You don't need one.
I use a heomostats with the tip sides ground down to reach inside the outer sight wheel and press the two detents in to allow me to spin the outer drum on the inner threaded section.

Also, a pair of long nose jewers needle nose pliers will do the same.  You just have to press the two detent in at the same time to allow the drum to spin.  If the drum will not spin with the detents pressed in (no longer locking in the outer drum grooves) then you will need to either soak the threads to break up any parkerizing that may be binding the threads, or use a heat gun if the threads have been loctited.


Note: I tend to blue loctite the drum on my rifles after they have been zeroed.  This takes out any thread play and holds the drum rock solid with not movents (canting).  If you don't own a heat gun, then using a blow torch is going to burn the painted numbering off the drum.  If you go this way to break the bond, then testers paint works great when it comes time to re-color the letters.