I do as Bugga mentioned, I cut the card stock to make my own cards. I get two cards out of a sheet of card stock that way. I have seen packs of cards/w envelopes at my stores, but they are more money. I get envelopes at Staples (100 in a box). Lots of stores online have nice ones, but the amount of cards I send, it pays for me to go and buy a large box.
Have fun! Glad you came and joined in. This is a very fun place!