The problem I have with this deal is he's not a real motivated seller, is a soft touch running out for 50% of value, not a good businessmanWhat I would do is to sell him on an installment sale at about 50% of market rend payment, divide 750 into the sales price

@Kenneth B.You are going to have to draw architectural plans before you start your addition, or have the drawings done by an architect/engineer who will put his/her seal on them.  

We want to make sure it goes smooth for them and us.What documents should we use to draw up the agreement?

@Abhay K. basically answered your question with the questions he proposed you need to find answers to and with - price = NOI/cap rateYou need to find what market cap rates are, take the NOI from the property and divide by the cap and you'll know if the $3.5MM is too much or if it's right ballpark where it should be. 

yes you can. you may need to provide evidence of your ownership and your constriction plans and engineers drawings showing your intent for site. they won't just move it wo good reason. even then get ready to wait.  

There are already some preliminary drawings. 

So back to the drawing board on how to copy my excel items and turn them into PDFs .  

What is it that draws you to the idea?

I have a deal closing this week that the listing agent did not update in the MLS as being under contract till almost two weeks after we had a ratified contract, and our MLS rules state it needs to be updated within 48 hours.Also the sites that draw information from the MLS like Zillow can just be dead wrong.  

The CPA is helpful as well in this, but we usually have the attorneys draw up the operating agreements and we usually advise them on if it makes pratical sense or not.