I don't know what the deposit is but even if you figure just supplies for some of this stuff it will add up. 

Is there more supply in the area?

GP’s should supply stress tests.  

Florida has over 1000 people moving in a day, our supply is almost non-existent compared to the past and even condos are giving amazing returns (example: we have a new condo purchased at $270k bringing in $4k a month in short term rental income). 

Especially post covid with all the supply chain issues that followed.  4-6 months is a much more realistic timeline and if the builder is off any worth you might have to get in line.  4-6 months is assuming you have closed on the property, permits are in place, a contract is signed, and the weather allows me to start today.  

We manage a few in NJ and are constantly shipping up and/or ordering supplies to be delivered to cleaner. 

I just refinanced an investors STR, he had to supply 12 moths trailing history of the STR income. 

If the city takes away the supply then prices will go higher as the demand will still be there in the short run.

Supply inching up.

@Aaron Dominy   Building supply chains have eased considerably in the past 2 months, thus the time-frame to build in Galveston has shortened.