There's a basic cafe and cafeteria in the main visitors' centre of Auschwitz 1 and a coffee machine in the bookshop at Birkenau. More options are in a commercial complex across the street from Auschwitz 1, although the quality of one the Art Hamburger is rather poor, but a cheap and quick eat. There are hot dog stalls and similar outlets outside the main museum at the end of the bus/car park.
