Anchoring is free, and there are thousands of places.
I've been there 8 times now on bare boat charters. Others here have more time than that. You can grab a mooring ball, but most are owned and will run you 25 a day (that's pretty much regulated). I suspect you can work out long term rates with the owners - they are all private owners.
Food cost more, especially meat.
If you live like a native and bounce around the anchorages it can be reasonable.
If you live like a tourist you need to bring a tourist sized wallet.
Medically speaking (I'm retired Navy) last time I checked there is still a hospital at Roosevelt Roads in PR
(only 90 miles away from USVI).
Based on what I understand having read your posts you have to do the USVI and the BVI, to not do so is just, well, wrong