This is what we bought when we finished sailing school in November. It was about $60 - it's a really nice detailed chart (thick paper, prob waterproof?). It's much more detailed than the chart that TMM sent with the guidebook. We also have Frank's map of the BVI's which is great quality and has snorkel/dive spots marked.
While the subject is up, should we also have a navigation app if some kind on our iPad? The boat were chartering is a 2013 cat - assume it has a pretty good GPS/charting system?