I've played games that use cards (Warmachine, Dystopian Wars) and ones that use books (the GW stable) but I've never played a game that required you to buy the cards in order to have access to the rules before. For instance, if I want access to the TIE advance fix, it's my understanding that I need to buy the Imperial Raider. And if I want to use that fix with say, an Accuracy Corrector, I need to buy a Starviper.
How would people react if (in a 'casual' game) a player was to simply write the costs and effects of a given card on a roster, instead of physically having the card at the table? Personally, I'd have no problems with that.