Agreed on the Burris mount- I have a $300 LaRue mount and a Burris and they both do the job equally well.
What MM size rings are you looking for ???????????
I have installed over a dozen MONSTRUM mounts and have found them to be aligned well according to my Wealer (sp?) scope alignment tooling. They are about 30 bucks on Amazon or better yet get one from the auction side of GB Holdings, Inc.