I realize there’s all sorts of regulatory hurdles with that (not wanting to discuss in this post, as I realize it’s a beast on its own), and am asking for guidance specifically on how you’d scope out the development costs.I’ve gotten the ok from the broker to access the building to begin some diligence.Wondering what some realistic next steps should be in projecting the dev costs, and ARV. appreciate ANY insight around this and thanks for taking a look.

So you'll either see 1) higher rents to compensate investment, 2) renting on the 'black market' to avoid regulatory cost, or 3) the investment capital will simply go to more investor-friendly areas. 

Regardless of the status of SB 9, building or buying an ADU is a regulatory play as well as a cash flow play.  

I welcome any feedback as to whether or not this would be a worthy use of my time, but from both a regulatory and monetary perspective these seem like preferable targets to me when compared to SFH. 

@Joe Splitrock also points out an extremely important point on Hawaii regulatory issues. 

I think the most important piece at the very beginning of your research is finding out the regulatory environment for where you want to purchase.

Believe it or not, this is still one of the most horrific and unscrupulous businesses in existence and sh*t like this happens constantly....the regulatory agencies that oversee agents are full-time slammed with complaints and hearings about stuff like this.That said, there may be more to the story...did she simply ask you to pay her more?

I can't speak to regulatory requirements, but obviously getting your ducks in a row there is a good idea.

I agree with other folks here (before you buy) regards to investigating regulatory climate in the Cities you're interested in: 1) Do you need a permit?

There are curative planning opportunities in this area, the most basic of which is for a non-resident alien (as it relates to the US) to hold their interest in US real estate through a US LLC that has made the election to be taxed as a C Corp.Investing across international borders creates regulatory and tax compliance obligations that should one should not attempt to DIY.