Appraising duplex and putting in an offer

[Gabriel Kreider]

I am considering putting in an offer on a duplex that was built only a few years ago. Each side has a rental history of being rented out for $1600 a month. They are about 1400 ft.² each with three bedrooms two bathrooms and a garage built on a crawlspace. If these were priced individually they would probably go in the 250 to 275 range. But individually as a duplex what would be a reasonable price? My current rental properties are town houses and I am considering house hacking and using an FHA loan to purchase this property. Someone I know interested interested in selling but it's not on the market(no asking price). What would be a good offer/what can I do to figure out what a good offer would be?