Alan-
Ideally, he would find a well-fitted northern boat that had been outfitted & sailed down to the islands, and then put up for sale by owners who decided ocean crossings just weren't for them. (It happens.)
Still, that could mean spending a month in the US Virgins or elsewhere, seeking & prepping a boat.
Petter, you might want to look at the pros/cons of different areas, maybe see what is for sale on
New and Used Yachts for Sale - YachtWorld.com and contact some local brokers, and then consider going down for a 2-4 week long vacation, with 50-50 odds of either just taking the vacation and flying home, or taking the trip and then plunging into the purchase and sailing home.
If the right boats (however your friend defines that) is advertised as being there, the odds are still maybe 50-50 at best that the claims are real or the price is right. Better if you can decide what is the right boat, and then get some recommendations for good brokers. Once in a while, someone actually is happy with how a broker has treated them.
Do make sure to find out how your home authorities will want the paperwork for titling and flagging the boat, in advance.