However, the cost and hassle factor is high. 

Rust Belt: Parts of the northeastern and midwestern US that are characterized by declining industry, aging factories, and a falling population.

Also we could get together and maybe work together.My background is as a an engineer working in factories for almost 30 years.

I tell them that their credit is only a factor I will consider.

If the only factory in town has closed up, and everyone is leaving, don't buy at any price.Consider your exit plan, if you are wholesaling/wholetailing, you need to know if there are buyers in the market, so look at the inventory qty. and compare it to the average sales per month. you will want that to be less than 6 months.  

Another factor is how fast do they want the project to get permitted.

There’s a reason they literally build these in one day in a factory 

Another factor is that something that has no cost is often thought to have no value as well.

Here it is.If you want to make the most money possible in building you must have a lot of capital Here is the list of what you need to do:1)Buy a lumber mill2)Buy a fitting and pipe fabrication factory in India3) Buy all the land available in your market area4) Get your own contractors license.

That factor is the elephant in the room, and it is called DEBT.