Zazzle. I got 100 cards printed front and back for less than $20 with shipping. They are always running sales so keep your eyes out for the coupon codes on the top of their home page.
When I ship a painting, I usually include a little card on which I write the title of the painting, materials used and then I date and sign it. A Certificate of Authenticity. I had been printing these from my home printer but I decided to have them printed at zazzle. I used the invitation option. Above is the side that I will sign.
And on the other side of the COA I just put an image so the buyer has a mini print that they can frame if the wish.
I started creating items with my images around mid December. It is free to join and to create and to post for sale. For their different items Zazzle charges a set fee and then you have the option of setting what you would like your profit to be. There is no overhead. If someone orders one of your items, Zazzle produces it and ships it directly to the buyer, they charge the money and deposit your royalty into your account. You do have to wait a couple months for the deposit. I did very well for the Holiday season. I had very little expectation because I figured all I was losing was a little time and it was quite exciting to see money go into my balance report.
However, I wasn't quite understanding my reports. It was showing up that I was making money off of items that were not mine. Ahhh they give you a referral bonus if someone goes to Zazzle through your link. After I realized this, I made sure I included my associate id # in every link I shared. It can easily be found under associate center when you go into manage my store. Now how this works basically is....If I have a tee and let's say it's $10 and I set my royalty to be $1, if someone arrives at this tee through one of the links I shared (with my associate reference #) then I earn a $1. If somebody else posts my product on their blog or webpage using their own associate reference #(kindly advertising for me) then I earn 50 cents and they earn 50 cents.
Also! If I share a link to Zazzle and someone goes to my store but decides not to buy an item but buys from another artist's store, I still make money.
January slowed down quite a bit but I am still getting a little activity and am going to continue with this for the year ahead. I have only advertised on my blog and on facebook thus far. In the year ahead, I am going to be periodically sending cards printed at Zazzle, to all my customers, with a little reminder on the very back of the card.
Since Dec 15th I have had 32 straight sales and 44 referrals.
There is probably more I could say about design options but let's start there.
Hope this helps and hope you all have a creatively successful and successfully creative year!