While useless in vanilla, I find I actually occasionally have a use for mind shields now that I have more equipment slots. Good on a shaken soldier. Good on a stealth mission as sectoid mind control (or even panic) is game over.
But they are really expensive. 20 supplies is a lot. 3 elerium is a hell of a lot. And stealth guys get killed a lot, losing you their kit. Given its use is not exactly game-breaking and it takes a up a slot, any chance of bringing it down to say 10 supplies and 1 crystal? (Keeping the corpse requirement is fine.)