I can tell you a lot more but don't expect it to help.

What should I expect the cost to be? 

Don't expect these people to have anything to do with you once the transaction is over and a lot of bitter, nasty fights along the way. 

Based on the development expected over the next decade, I believe it's a great area to invest in. 

I am wondering how much expected weather of an area impacts your decision to invest in a specific area.Recently looked at Census data which shows that people are predominantly moving to Florida and Texas.

If we do a Self Storage development we expect a 400% COC return.  

Perhaps do a case study with a hypothetical deal you think is typical for what you are looking at and compare it to the alternative investments you might use and their expected returns.

Improvements took longer than expected.

Expect rates to be higher than "typical" financing programs - right now, I'd plan for at least 8%+ depending on the whole scenario. 

I'm not sure what you've heard or are expecting, but as with anything in life you generally get out of it what you put into it.