I just brought up an installation of Gallery2, and I think it's great. It's most definitely targeted at community photo albums, rather than commercial use. It's got a shopping cart to hold selected pictures, and users can then submit the images to a third party (i.e. Shutterfly), where prints are made and sent to the buyer. The prices are reasonable, but I haven't seen anywhere that you could modify them to make a cut.
I've only got one image in there, but you can poke around and check out the cart, and the Shutterfly connector if you're curious. Here's the link: http://gallery.teamshocker.com/