Can't give you specific dollar amounts, but we found the hypermarche in Tahiti, near the marina, to be very expensive, say 150 - 200% of North American. On the flip side, it was the most incredible supermarket I have ever seen. Take an immense French supermarket and drop it in the middle of a tropical ocean and you get the idea. The market in downtown Papeete was also very good. Baguettes are cheap though.
Back in the water in Grenada - with new main and #2 and cockpit canvas (Santa came early). Will spend the winter and early spring in the Caribbean and then head to Bermuda and the northeast US. Still trying to decide if we will bring the boat to Canada, either in 2015 or 2016.