For the Lillies Clefairy ex SAR specifically, the JPN version at 28,000 (~$190) compares favorably against the ENG versions lower market price
This means that aside from ACE SPECs specific to certain Pokmon (Crystal Wall, Crystal Edge, Victory Piece, etc.), any ACE SPEC can be played in ones deck
Its attacks had a relatively low cost and dealt a ton of damage
Its not just the two games, either, as Magic Online still exists, and is still fairly expensive and deeply unfriendly to beginners too
As a follow up, I posted this question on the "YuGiOh Duel Generation Duelist Kingdoms United" Yugioh Duel Generation fan group on facebook, and someone name Mera Utopia replied with this: "A decent dragon deck with only "free" cards is possible