I bought ranks for the extra enderchest slots, /pv, and most of all /fly. Now no ranks can fly around to make bases to make the game more balanced. A good idea to get players ranks worth the money is to add /pv to lower ranks and higher ranks get /pv 2 or maybe a 3rd personal vault. A good way to balance value and not stacking everything up over time is to make no spawners can be placed in those personal vaults and only in the enderchest.