As others have suggested before, I also feel that the main cost is not in the shoot or the materials, but in the time invested in preparing, post-paring (photoshopping to get something like RJBender posted and getting the prints), then trying to get those prints sold & the money actually in your hand.
I shot a friend's wedding and convinced a few other friends to invest in me and in a high quality hand-made leather book for presenting the wedding album. What I didn't factor in was the time it would cost me. I'm guessing afterwards it was somewehere around 100 hours. I was happy with the result, so where my friends, and the experience is great, but the next event, I'll be charging per hour.
If you can make sure that 1) all prints are pre-ordered and cashed in by the church (people will have a harder time to say no to the church if they already ordered), and 2) your work is limited, then I'd say: go for it.
Peter.