Your total basis will be the purchase price plus any cost to acquire (like commissions, fees, transfer taxes etc.).

Offering 300k on a 390k house is not going to make them feel like we have a "win-win" scenario here. 360-365k allows me to offer them a price they'd walk away with if listing with an agent after commissions, and still gives me some initial equity in the property.Again, in a lease-purchase, I am in no obligation to purchase the property, it is an option.

Its value has increased by at least $100k since we bought it, but if we were to sell it and not do a 1031, we'd only get something like $80k back after taxes and commission.  

The reason many are agents or related to one is to save the commissions when purchasing and selling. 

The seller has representation and the seller pays for the commission.

She was either making rent off of us by staying in the rental townhouse longer, or she was making commission off of us if we bought a townhouse through us. 

Do I pay commission for somebody coming to me to buy?

After I sell he gets his 225, I get my 300 back and we split the 125k profit minus closing and commissions - call it 50k - so we split 75k. 

For 2018 I’m being charged $1326 by “United States liability insurance”  includes a $35 commission to my Allstate agent. 

The difference is actually our commission.