Well you say that but when we were kids in the 70s my Mum used to make an incredibly cheap ice cream involving whipped evaporated milk. Not sure what else was in it but we hardly ever had bought ice-cream because of the expense (we weren't exactly poor but there was no spare money at all) and we absolutely loved it. It used to come out of the tiny freezer compartment of our fridge rock-hard and we would sort of slice it out of its tray (she used the ice-cube tray with the squares taken out). Quite often it had separated because she'd over- or under-whipped it or something so the bottom layer was heavier, but hey, it was ICE-CREAM!!! YAY!!!! Our requirements were merely that it was cold and sweet.
I feel quite nostalgic now, might ask her for the recipe so I can goggle at it. Those were the days.