I have a 9 acres in city limits in Texas and I want to build a mobile home park

[Stuart Edwards]

I have a owner of 9 acres in city limit in the north west/central Texas who wants to sell the property. What type of contract do I use because I was recommend by my lender that this will be a commercial deal that will take longer then a normal house contract. I want to build a mobile home park and a steel building  for a park office and some other amenities but I don't know what is needed or how costly it will be.
I do know the cities codes and the zoning needs for a mobile home park. Currently the property is zoned wrong because of this I have reached out to the zoning department to work on that. I really need to know the numbers on the building costs so I don't get robed by the contractors or some contractors contact info that work well and keep it with in budget.