I have avaliable my latest "Abstract-y paintings" originally painted on Yupo paper. Quite different from traditional watercolor paper. They are avaliable in note cards and greeting cards. 
The note cards are 4x6 and come with envelopes. The greeting cards are 4x6 mounted to a 5x7 cards stock and come with envelopes.  In the drop down you can choose the amounts and size you'd like.