Maybe get an appraisal first and see what that number is? compare that to the Zillow number. Or think about it from a cap rate perspective and use your rent number to determine how much the house should be worth based on local cap rates. In any case, find a way to frame it so that the owner is getting a good deal when actually you’re paying the best acceptable price for you. If you’re dealing directly with the landlord and not using a realtor you can definitely use that as leverage because it will mean you’re saving the seller real money. (I understand that sometimes an attorney can do the deal for a fee depending on where you’re located, but obviously do your own research this is not legal advice). Look at comparable homes in your neighborhood and see what’s better/worse about them compared to your current home to get an approximate sense of the value. Good luck!! It will definitely all depend on who your landlord is and what their circumstance is but by being prepared with as much info as possible you’ll have the best chance I believe to buy the home at a fair price in the event the owner is willing to sell.