Why would you need to replace the armature every weekend? You gotta remember that if you are cutting your mods every third run or so you are only removing a VERY small amount from the comm.
As for brushes, I know there are some out there that can be run up to 6 times before needing to be replaced. (I'll try to find the manufacturer and part number.) They lose a little in performance toward the end of their life but it's not REAL bad.