It wouldn't motivate me. It's not the cost that's the issue. It's the wasted time and paper spent on cards for people who don't pay me any mind the rest of the year. If they want to talk to me, they know where I am.
I don't even like receiving cards from most people. I'm like, "Really? You haven't said one word to me in person, on the phone, or even in a text message for three years, but now you're sending me a card with a picture of your family on it? Hey, congrats on the new kid that you didn't bother to tell me you had until now."