Wooohh! more cards, when theres enough, you should catagorise them into more raritys and have an auction/card trade... or would that be too hard?
Card trading/auctioning between accounts has been vetoed into oblivion by both Zanz and the community -- it would just promote creating multiple accounts to funnel rares and Nymphs into if it were to be implemented.
Right now, we already have five different rarity categories:
Common (available in Bazaar)
Rare (Available only in spins -- this includes Shards (from T50 only), rare weapons, Squid, Pharaoh, Miracle)
Super Rare (Available only from Oracle and from winning tournaments/leagues -- Nymphs)
Ultra Rare (Available only from winning tournaments/leagues -- Mark cards)
Secret Rare (Available only by donating to Elements -- alternate art Chimera)