Yes done that here in Bahamas. As you may know the Bahamas is made up of around 2,000 islands and islets over a vast geographical distance so plenty to buy etc.
Some have been on the market for ages. There’s a reason for that. Others are not on the market but the owner will be very happy to unload them to the gringo.
You need money and I mean real money outside of the often soft purchase price just to maintain and build on an island.
Yes and no. Depends on what you want to do with it and how posh you want it to be. The real essential infrastructures are just a few and not that much expensive with today’s technology.
If the island does not have infrastructure already get ready to have to build a sturdy dock,
That’s essential for the construction phase. However, you could plan for one to be abandoned to the elements after 2-3 years. To build a really sturdy dock is incredibly expensive, but mostly unnecessary (especially with a low budget).
If you observe the satellite images attentively you will often find the foundations of an old dock somewhere, that’s the best place where to rebuild it and you can save some money.
Never touch mangroves. Most islands are (rightfully so) environmentally protected, so you can’t just go there with a bulldozer and clear everything. Btw, if you have that in mind, forget about an island anyway, unless you are a Bedouin and live in the UAE.
and pay through the nose just to get labor
If you find it lol
and heavy building equipment onto the island.
That’s not so terrible, as you will bring most of it on the island with a barge just once. Better to keep some heavy equipment permanently on site, to be used for maintenance.
The markets are littered with half finished dream islands where people have given up or ran out of money or failed to even start making it habitable.
Sad and authorities are co-responsible for this. Same happens onshore though.
They all underestimated the enormity of a project for even a close to shore island.
It’s not always just a question of money. You need to be the right person to own, develop and operate an island.
Just basic things like a water filtration system,
It’s not really a big thing, but you need a backup (like for everything else essential for survival).
pumps, power etc can be a head ache.
Sometimes you can lay a submarine cable, which is not terribly expensive (if it’s allowed).
Not to mention the often outrageous importation costs
There are facilitations. Including in the bs for the family islands.
matched to the almost heart stopping costs of transportation too and from your island.
It’s a matter of organization, but yes it’s much more expensive to move barges than trucks.
If however you can find an island where a home and infrastructure has already been built it may be a good purchase.
In such cases the price will be outrageous.
Just remember there is no ambulance service
Not that it’s much different on the bs family islands
Police always comes after the event, so it’s useless.
and no one coming to help you if you break your leg
You need to plan for such events.
or if intruders come on your island.
This is the most serious threat. However, what happens on your island stays in your island. 99.9% of the times you will just have to deal with curious tourists, not necessarily too nasty.
You would need satellite phone and internet service which is often extortionately expensive.
Ever heard of Starlink?
People I know that have islands have a full staff with a boat with captain, helicopter pad, medical center, maintenance personnel and a ton of machinery from filters, sewage pumps, vehicles etc

.
You know rich people. I know modest guys who happily live a simple life on their island.
P.S Maybe just a simply day island very close to sure that you visit during the day and come back before evening will work.
Nice idea, but you don’t really need to own an island to be able to enjoy it for a day.
But if you want something to live on then please ignore purchase price even if 6 figures and look at full maintenance costs, no insurance etc.
Word. Unless it’s just a trophy property for you.