And there may be somewhat of a combination of site improvements included (sewer/septic, water service, etc, to the MH sites).Then the income approach would be looking at the cap rates, as Roger mentioned.

However, there are some out there that will use AirDNA type sites to calculate income. 

Could you please rank yourself amongst them so at least I have an idea?   

Online Auction Sites - Realauction.com, LLC 

Many of the moderators of the site have experience with seller finance. 

get a copy of the agreement used by agents in your area and merge it with wholesaling agreements you can discover on Jerry Norton's site.

As for comps, if there are other modular homes in the area you may want to check sites like Zillow or Redfin to see if there is data on those properties. 

True foreclosures are all cash purchases so if you don't even want to pay $25 for a list or for access to a good site, you are probably starting a long climb up the wrong tree.

Why are you posting a diagram of BRRRR on the site that created the acronym?

Detailed Due DiligenceConduct in-depth due diligence, including background checks, reference calls, and site visits to assess the sponsor's operational capabilities.