I'm not sure of availability of Disney photgraphers at VB, though I'm sure it could be arranged through Disney.
This past December we were at WDW staying at OKW- I looked into having Disney photograpers take Xmas photos of the kids.
It took me about 2 weeks of phone tag to finally speak with Diney wedding photo services. The service that I would need was considered a portrait shoot, it would have been approx $250 sitting fee for a max number of 8 people and If I remember correctly only a certain number of pictures would be taken.
Compared to the professional photographer I have used to photograph my kids ($150 sitting fee and approx 4-5 rolls of photos)- I found this hard to swallow- especially knowing it takes quite a few photos to get one or two good ones when taking pics of kids.
If it were me, I would compare Disney services with local professional photo services. As I would love to hear what you decide and how the pictures come out- I'm thinking this might be a fun idea for our next VB vacation!