Cost to build
I read the BongoBongo blog when it was current and looked forward to every post.
Remember this was over 12-16 years ago. The difficulties of their ST John building are very different from STT/STX, in a few notable ways. The cost of concrete and scheduling problems in particular. Also they were building a rental villa, very high end, for a discriminating STJ demographic that now rents for $3500 -$6300 a WEEK.
No question that it is an entertaining and well written building blog worth reading, but you have to consider the relevance to your project, how times have changed, your own design and needs and the island you plan on building on.