This is my first time deciding to build a house and attempting to sell it from another state and I wanted to check to see if someone familiar with the Bella Vista, AR area could confirm the sell prices given to me are accurate. 

Best way and most accurate to get help finding the owner of a property other than using a skip tracing website?

Before you consider the above accurate in your state, find an experienced attorney who specializes in MHP leases.  

If I purchased a SFH for $30k I would be very happy.Along with that you would need to make sure that your cash flow calculation is accurate. 

I am trying to be as accurate and realistic as possible and certainly don't want to buy a house just to buy a house.

In reality, this is not going to be accurate.

Given the age and lack of amenities offered at these buildings, $750/month might be more accurate meaning that after complete renovations, this portfolio could gross $13.5k/month and $162k annually. 

The diversity angle alone cannot accurately assess the viability of your venture being successful.

I'm worried that I won't be able to accurately predict the total cost of this subdivision project.

It will help in presenting accurate info to a lender and will only increase your credibility.