On the subject of selling the playing cards, the Seattle Flower and Garden Show is coming up in February, and there will be many vendors selling all kinds of gardening related stuff. I imagine there will be other spring shows as well, in other cities. Have you thought about approaching some of the large nurseries that typically have booths at these shows and selling wholesale to them? Also, some organizations, like Seattle Tilth, have a lot of members interested in gardening, climate change, and other areas of interest closely related to permaculture. They might be interested in selling some cards at their booth.
Although it's a little late for selling Xmas presents, a lot of people get money for Xmas and buy gifts for themselves in the early part of the year, so I would think you (or the folks you sold them to) could expect decent sales figures through spring.