Another thing to consider, not as a replacement for the professional photographer, but as an addition... ask all your friends who have cameras to bring them and take LOTS of pictures at the wedding; and for those who do not have cameras, perhaps you could buy/beg/borrow/steal a collection of inexpensive auto-shoot cameras for them.

You will get pictures that the professional guy didn't get (he can't be everywhere at once) and almost certainly some of them will be pretty good. At the very least you will get to see the wedding from some different viewpoints that you otherwise might have missed.

tanstaafl.