There's a company that says it does printing on recycled matte cover cards in a minimum quantity of 50:http://www.psprint.com/greeting-cards
I haven't used them so I can't comment on their quality.
I can tell you that Shutterfly.com makes cards in quantities of 1, 5-10, etc. on "premium cardstock." I couldn't find any recycled papers advertised there, but I have used them and was very happy with the quality of the cards they made for me.
Good luck on your search... what a wonderful gift idea!