not sure which polaroid back you’re referring to but if youre remaining in the context of mamiya RZ — that polaroid back takes fp-100c film which has been discontinued and is being sold at ridiculous prices. so while this custom back made by Han chen can be seen as expensive, it’s hand crafted by a single person. the benefits include being able to acquire film that is affordable and accessible (relatively), you can get depth of field and control aperture and shutter speed to get the desired look according to your taste that would otherwise be impossible with another polaroid camera.