the spa is what got us, 2 massages on Castaway Cay, the surial experience and some products + tips was over $500.
We didn't drink that much (a glass of wine at dinner, a few drinks at the entertainment) - I think about $80 total
We spent over $200 in photos - they turned out WONDERFULLY and we are lazy about taking the kids in here so I justified that cost as a year's worth of sittings at home.
We bought a few things on-board - got some great windbreakers for the kids at 1/2 price ($24.98) and one for a neighbor friend, a coffee mug, signed map, pens, etc. A t-shirt for everyone on Castaway.
The only excursion we did was Captain Marvin's and it was $100 for 4 (DD was 3 years old and free and probably enjoyed it the most of all of us, although we all loved it), plus we tipped the boat crew ($10) and bought the video.
We wandered in Key West, had some pie and drinks. We didn't even get off the ship in Cozumel (btdt) so that was a cheap day
hope this helps!
btw, we charged almost everything to our room and I brought $50 in ones for tips and used very little of it - we only had room service a few times (3?) and tipped the porters with $5 + some ones to equal about $2/bag. I won't take as many ones this time.