5000 coins isn't THAT many to begin with. Though, so far, not including the reward cards, I have 3 Cross-Wing, 2 Wild-Horn, 1 Rock-Lizard, 1 Golden Homunculus and 1 Gamushara. RNG is RNG, though I have a sneaking suspicion that your "rank" in the event influences how likely you are to pull certain cards. (There's no real reason for them to be there otherwise, aside from to mimic PvP ranks.)