the original idea, which i felt was flawed and very scammy was that they wanted some crowd funding.
but what would be the great plan is not to physically buy an island. as thats a billionaires wet-dream, but instead make it the most bitcoin friendly island there is.
the guys behind the Indonesian exchange can do all of this without crowd-funding. they simply use their exchange as the 'bitpay' equivalent service for shops on the island to convert. (also how the exchange makes the profits to afford the promotional stuff)
all they have to do is set all the shops up with their exchange and offer a QR/fresh address service that links to merchant accounts. this costs the exchange nothing to set up, bar a few lines of code. and walking around the island drumming up business has no costs either.
the only costs would be labour which they recoup from the merchant services they offer on their exchange.
if they want to have an office, again they dont need crowd-funding, as the exchange is already making profits so its not like they are a start up. they simply drop the current office rental, and move to another building that is on the island.
so now we are all on the same page that crowd funding is not needed, let move onto the promotional side of getting the shops on that island to accept bitcoin. then once the shops accept bitcoin. the staff who live on the island will find they can buy their food and clothes with bitcoin as... the shops they go to accept bitcoin. meaning the amount of bali legal tender will slowly decline to not being required at all.
That could be done in a lot of places. The little town I where spend my vacations in Florida would be a great candidate.