The shareholders own and build equity while living in the properties. 

This means that each owner is a shareholder and subleases their respective unit from the corporation (does not own their unit specifically).  

Generally we zero out income from the C corp as salary to the two shareholders so we don't get double taxed.  

., may be in an individual's name, but if they are not the major shareholder, there is really no decsion making delegated other than hold or sell....

Part of being an S corporation (or taxed as one) is that the Shareholders are required to take reasonable wages. 

A partner without financial heartburn isn't a partner, it's an employee with way too much controlling interest.They cannot be straight up shareholders without a buy-in.They can be employees.

They have a duty to their shareholders and in many circumstances a duty to the previous owner to maximize recovery and mitigate loss.

As a result it would be difficult for them to properly do the books.Regarding whether the costs are high or not...it depends.It depends on several factors1) How many shareholders are in the S-corp2) Are you only doing business in one state or across multiple states3) Is tax strategies discussions including in the pricing?

Fair Credit Reporting ActA consumer protection law that regulates the disclosure of consumer credit reports by consumer/credit reporting agencies and establishes procedures for correcting mistakes on one's credit record.fair market valueThe highest price that a buyer, willing but not compelled to buy, would pay, and the lowest a seller, willing but not compelled to sell, would accept.Fannie Mae (FNMA)The Federal National Mortgage Association, which is a congressionally chartered, shareholder-owned company that is the nation's largest supplier of home mortgage funds.

You could make them shareholders / partners in the deal.