You're probably disagreeing right now, but hear me out. I'll get right to it:

At the end of all boss battles except Snarbolax, give them a chance to drop a strange Mineral (Included with boss token, everybody in the party gets one, very rare), that comes in 3 different sizes:

Small - Most common of the rare (If that makes sense)
Medium - Average of the rare
Large - Rarest of the rare (Like meat right off the cow)

When you get a Strange Mineral, you can go to Wegner and he'll transfer some of your mist energy into the crystal, for a fee.

Small Crystal: 10 Crystal Energy, costs 30 Mist Energy and 700 crowns to energize
Medium Crystal: 25 Crystal Energy, costs 50 Mist Energy and 2000 crowns to energize
Large Crystal: 50 Crystal Energy, costs 70 Mist Energy and 3000 crowns to energize

I think it's a fair trade, and one could hoard the crystals and energize it when they don't have time to use their Mist Energy on runs, or they just don't feel like playing.

Again, I know near nothing of the CE economy, but feel free to discuss any changes you might add.