It is suggested in this quote from Majoru Oakheart: "-They are intended to be opened at the table(and I got the implication that each player was intended to have his own stack of the cards) because that way you have no idea what is in your own deck until the random events actually happens."
Each player is intended to have their own stack and they are expected to be opened at the table. This equals each player buys a new pack for each game. I'm not sure how to read that any other way.
I don't think most tables would allow one player to use a pack, when the others don't. Its the sort of feature that is either everyone uses it or no one uses it.
Thus, the intention seems clearly that every player buy a new pack for each game. Obviously they don't expect every table to do this - I'm not suggesting its a mandatory part of the game. But those that do choose to use them, this is how, according to Majoru, they are intending them to be used.