Make the offer fair but as is where is, pre approved or cash for financing and no BS at all for landlord is your best bet. Landlord is already making money off the property and may have no interest at all in selling. I have received lowball offers to buy places I rent and have said, eh, no thanks. I have sold houses to tenants where they get a good deal, I get a good deal and it went very smoothly. If landlord bought the place on a 1031 exchange, they may never sell. It costs nothing to make an offer.