i had seen some last year, at jumbo. they were pretty lame i must say, i went to a paper store at unicenter and they had some nice paper to make your own, but i am always on the look out, if i seen any i will post it...
Unluckily there is no Hallmark store here.
Some boxed Christmas cards are sometime sold in the street, to collect money for the Hospital Garraham, Red Solidaria...but pretty lame too.
This is a tough dilemma. Since I've lived here for less than two months, I don't know much about this either. There are services online that let you make your own Christmas cards, then, they print them out and mail them for you.
Boxed no but in packets of 10 or so yes in the Unicef store at end of Belgrano. They also customize them for companies in boxes of 100...great service which I have enjoyed every year...hope it helps.