Photo's are $20 for an 8x10. You can then purchase other sizes of the same picture (5x7) for less money. You have to purchase the 8x10 first though. If you don't purchase the 8x10 first, you can't purchase any other sizes.
I liked several shots when we were on the Triumph in December, but couldn't imagine spending so much money. Some people have no problem spending a couple hundred dollars for pictures. Some do come out nice, and other don't. I would recommend waiting till the end of the cruise so you can pick the best shots. There are photo ops all the time.
02/13/05 Carnival Miracle
12/27/03 Carnival Triumph
02/15/03 Carnival Inspiration