Check out iwifitravel.com. We have had good luck with their service in multiple Caribbean location including the BVI. They ship you a
MiFi device that is ready to go when you arrive and will let you connect up to 10 devices unlimited for about $10/day plus shipping. We have one for our trip in February and it only cost about $12/person for the week which is not bad. It has been fairly reliable for us and even able to stream a little at times.

We use our phones as backups if necessary. Renport is usually $240 for the week which uses the same cell service. One less thing I have to do in the marina before we cast off.

Brett