Hand painted post cards

A few months ago I went to my favorite art shop (PNA in South Africa, they are specially good in Somerset West/ Strand area) and came across watercolor postcards- they are blank postcards that can be customized according to ones wishes.  I thought its such a cool idea. So here are some of mine:

They all are size A6. I find painting these fun as they are small and quick- well, compared to what I am used to. All are painted with acrylic, but i do think of giving an oil paint a try too. The only worry is if the oil is going to seep through the paper?

Now I need to figure out what to do with these postcards- cos at the rate I am going I will soon have a full house with these. I was thinking of maybe offering to do these for charity- in that case everyone benefits- charity with earning some bucks, me distributing my work. I think that's a great idea, what do you think?