The answer is actually very simple: it's market dynamics, the demand makes the price (capped by the non-profiteering rule).
The more informed and objective the demand is, the fairer/more consistent the price is.
Unfortunately, in a relatively small market as M2M is, the demand is rarely informed or objective, there's a lot of people buying out of impulse or hype and that can cause price aberrations. I recently saw a TC selling for 1200$ (seller had bought for that much out of fomo at the time) where it's fair market value would lie approximately half of that price. But the demand seemed to be not informed, noobish frenzy and fomo allowed for that price to stand.
On the other hand, just yesterday a ALS datograph sold for a more than fair price considering the rarity of the piece.