For prints, it would be especially nice if customers also got a frame. Without a frame wall art looks cheap. It's no fun buying a beautiful poster and not being able to display it. If someone knows how to economically ship a frame, selling it together with the customer's choice of flickr art would be interesting.
We did this with Yaperture (http://yaperture.com), sort of. The costs associated with the buying and shipping of frames was way too high for the average consumer. So, we compromised and sold the photos with thick museum-quality matting.
That sounds good expense-wise. Maybe also include a rectangular sheet of clear, flexible plastic to serve in place of the front glass. And one for the matting.
