Question about buying troops in arena?

[GemsCollector]

There was something about post-arena troop cost in info about 1.0.9. Here it is:

@Sirrian

Arena:
[…]
~ The purchase price for troops you already own has been increased from 1 Gem, to be in-line with what you would pay for a key.

I think the cost was 20 gems when I finished and had all 3 troops on lvl 15 or higher. I may be mistaken though.