My town has a Guernsey farm [1] just outside it, so that milk is available at our local food markets. It's wild how expensive it is. Like, the regular cheapo milk at the grocery store is $4-5 for 4L, and the Eby Manor milk is $5 for 1L, basically four times the cost.
Now, they're a small time operation doing a specialty product, so I'm sure that contributes a lot to this cost bump— they justify this mostly by touting health benefits rather than talking about the sustainability of their operation, but I suspect that getting many animal-based food products to a more sustainable place would require a similarly eye-watering bump up in price. Which is, of course, part of the argument for going part-time vegetarian/vegan— get used to the idea of meat and animal products being something we enjoy once or twice a week or a few times a month, rather than multiple times per day.