As a non-attorney, I would just say give them a few small additional things to do, such as approve the underwriting, rent survey's, site visits, review monthly reporting, etc.                                                         

Probably half the price of a platted lot survey, guessing.

.- buy your own survey- if the listing agent had a preferred title company listed in MLS, be sure to put it on the contract.- offer to pay for the title policy- do not include an option period.

Title insurance will require you get a survey anyway. 

Elmer Morales is the founder of eHomes and has much experience and unique relationships in the industry making his team the "Best of Zillow", based on consumer surveys, putting us in the top 1% of Realtors in the country. 

Quick survey:Would you rather own 5% of 80 units OR 75-100% of 10 units? And why?

She also thought there was a potential to split a lot off the property which I have found that is not a possibility by the building dept. or a survey co.My intention was to offer her 130,000, utilize a hard lender for this and 50,000 rehab and I have 50,000 for "skin in the game".

Proper due diligence includes an Asbestos Survey, Lead (paint and ceramic tile) Survey, Property Condition Assessment (ASTM E2018 - I helped write it), and for many properties, a Phase I Environmental Site Assessment.

I'm not sure what @Trace S. used but there is tons of data out there.IMO never substitute data from state wide or metro wide averages for your own geographic rent survey.

Do yourself a favor and do a rent comp survey of the area.