I found a sight for provisioning and a sample list of grocery items for St. John. (villafoodvi.com) Just thought it might be helpful for planning on food and cost.
We used Villa Food to provision our villa last November. Ali does a great job and it was wonderful to not have to run out to the grocery store after our long day of travel and the ice cold beers were a welcome sight to all! I highly recommend her service.
We used www.villafoodvi.com in December!! We got a breakfast package and a lunch package, along with our frozen food we brought for dinners and we were set for 10 days!! Wonderful to have food/beer in your frig after a long travel day and having food the next morning - relax and get on island time right away!!