The images show cards with just the suits on them. Is that how the game is usually played?
It seems that playing with a normal deck (suits and ranks) would change the gameplay considerably. For example if you see the A-2-3-4-5-6 of one suit, trade them away, and later see the 7-8-9-T-J, you can be certain it's the 12- card suit. Or more realistically you can do a probabilistic version of the same reasoning by seeing some cards and asking other players questions like "do you have the 8 of diamonds".
That's a valid observation, but if getting a 12-pack of identical decks is not a problem, it's enough to build 13 custom decks (all Aces, all 2s, etc).
Edit: if the players can announce only what suit they are buying and selling but do not show cards to the others, it may end up difficult to deduce what cards are missing, because only the buyer and the seller know the value of the traded card.
It seems that playing with a normal deck (suits and ranks) would change the gameplay considerably. For example if you see the A-2-3-4-5-6 of one suit, trade them away, and later see the 7-8-9-T-J, you can be certain it's the 12- card suit. Or more realistically you can do a probabilistic version of the same reasoning by seeing some cards and asking other players questions like "do you have the 8 of diamonds".