Don't waste card stock until you're way along in prototyping. I'd buy some sleeves and some trash magic cards, then print your cards on paper and sleeve them in front of the magic cards.
This will make it easy and cheap to playtest changes.
Thank you. I have done the paper print prototypes, sleeving them and giving them some rigidity using playing cards. The game information on the cards is unlikely to change but the ruleset is in playtesting. I was just looking ahead at the next phase of development, going on the positive feedback I had recieved so far.