That's pretty much what I was thinking (Destiny)

by CruelLEGACEY , Toronto, Monday, June 22, 2015, 16:57 (3681 days ago) @ stabbim

As an alternate idea, instead of locking out per character or per account, they could just have it cost a very high amount of glimmer or strange coins. I suppose the exact gating mechanism doesn't matter much.

I was picturing Etheric Light showing up right along the top row of Xur's junk, next to the weapons, armor, and engrams. I think it would need to be expensive (30 coins, 50 motes, whatever) but should be available every week nonetheless. By selling it in exchange for a currency like Coins or Motes, players would be able to work towards it by playing almost any activity in the game. Slowly, but they could still be making constant progress.