So, I decided to make actual postcards out of my illustrations. I found a printing company that has three different types of paper and I'm ordering about 100 of each. 100 is their minimum order. I should be getting them some time next week and let you know what I think of each. After I choose the paper and see the print quality, I'm going to order more (I have about 16 illustrations that are in my card rotation).
I'll put off sending out the $25+/month Reward Envelopes until I have these postcards in my hands.