The problem in Key West is not only the property prices, astronomical insurance, and potential disasters (I lost my home in Hurricane Irma), but there are extremely strict city regulations and laws in place for STR’s.  

My guess is that new regulations will pass in the future and put a stop to the huge tax hike but not sure how soon that will be.https://fox2now.com/2019/05/14/st-louis-airbnb-hosts-to-pay-increased-taxes-after-city-reclassifies-residential-properties-to-commercial/

Portland is in a unique spot right now working through some rental regulations (both city and state-wide) that have the market in a bit of a tizzy...some are pulling out, some buying in, and some are just sitting and waiting.

. $100k is a lot and numerous companies would love to help you... so be careful. 

Anything over 30k in rehab costs is a bit more complicated of a transaction and requires more fees and regulations. 

There are numerous variables to take into consideration when analyzing any property.

I’ll check the regulations for S8 and I’ll plan ahead.

BUT, the permit process is town/city regulated, so yours may be different.

Not only the STR market is not yet mature it will always have some sort of instability for several reasons; cities regulation change making big increase or decrease in a location leading to new hosts.

AU laws are certainly much more stringent and regulated than the US.