You can run a RentRange or RentFax report They tell you vacancy rate trends by zip code.

It also has strong economic and demographic trends with a growing population and jobs.

Tariffs are a factor, mainly on certain materials like steel, but not a huge factor overall   Without knowing many of the specifics, or finish out levels of your project, I would expect to be able to build something like this for around half of what you are being quoted.My guess is the reason for high quotes is that because the demand for construction is so high, and contractors are backed up with as much business as they can handle, they are throwing out very high prices.I would keep shopping, and if you have experience, consider GC’ing it yourself, and hiring the expertise in the places you need it.

As for mobile homes, if they have no steel girders under them, called stick built, they do gain value if set on a foundation not in a park.

Cost of steel and labor are up for developers.Unless the land is dirt cheap then do not look for a quick sale.

We're home to Winchester ammunition, a couple of Steel Mills, a glass factory, the box company, all of which are gone.

I use to honestly get a little upset because I was feeling it was going to make investing harder for me or I was going to have to sit back until this trend slowed down or stopped.

On BP the trending minimum is $100/door.

The guys you see working on the large upright structures of steel at a petrochemical refinery. 

Learn to follow Trends.