All items are available at: www.tshirtstudio.com/marketplace/ourbigbook-com from tshirtstudio.com. Each sale includes a 5 dollar/euro/pound donation to the project.
This is a reasonable website.
It is a shame that you can't easily drag and drop move/resize images on the web UI, which has led us to do that manually on the in the source images.
But still, relatively easy to use, and easy to setup a marketplace in.
Another downside is that it does not seem possible to edit existing designs, so it is a bit hard to know exactly what you had done when it is time to update things.