Have you tried making your own nut milk? It depends on where you live what nuts will cost, and everyone's taste preferences differ. Almonds are common, but not exactly environmentally great as they need a LOT of water. Cashews make very savory milk, but they have a lot of fat. Where we live hazelnuts are plentiful and we like the taste.

We soak a handful in a glass of water overnight, then my wife uses a few (not) secret spices, some magic, and a blender. Three minutes later we have a liter of nut milk for less than 50 cents.

We reuse glass bottles so there is extremely little waste. Storing a bag of nuts is also much easier than multiple cartons of soy, oat, or nut milk from the store. We have found absolutely no downside.