RW had a great idea before with fusion stones that you could pick your own green stats, I think we need to revisit that idea.
Latest Black Codex vendors from the previous 2 or 3 zones would remain the same.
Black Codex vendors from ToSH to Grotto would sell MANA stones with random stats for 1000 mems.
Black Codex vendors from HotO to SC would sell MANA stones with random stats for 500 mems.
The idea is to help gear the mid-level guys with stats to help them gear and move on up. Right now, nobody cares about previous instance stats because it's easy enough to get high level stats @ 55+ through shell events. But if players are capable of earning at-level stats by farming instances, I think we'd have a happier mid-level group of people; as well as more instance farming @ level.
The idea is that people would get t4 or t5 mana stones w/ stats so they would save on 1 puri & 1 charge from the pull. Initially, it would seem like a loss to GF, but I think a happier group of players = players more willing to buy diamonds later. As these players advance in the game, they'll get familiar w/ instances since they'll have to run a bunch to get those mems. More importantly, they'll get to know the most important part of the game.. how to play your toon & not just do dailies/mini's ad nauseum.