To confirm earlier tests, I just started a new game on easy and cleared the cell block. On level 1 the cost to unlearn a skill was 33 gold; on level 2 it was 133.
Cost = (100/3) * L^2 [color:"#3A495A"].....[/color](rounded down to the nearest integer)
An earlier version had a 50k cap for the maximum, though that may have changed.
In the demo this cost was double what it is in the game.
