Would you buy human milk if they sold it in the supermarket?

Strongly depends on how it's sourced. Would definitely give it a try if it's excess from a milk bank that's about to expire or if it comes from cultured human breast tissue in a lab. Would not try if it its from some random person or otherwise unclear origin though.

Also wouldn't make a habit of it, there's probably infants who would benefit from me not making it more scarce and expensive than it could be.

No, I'd be worried about viruses. With common animal milks, I know there's almost zero chance any viruses present in the milk are capable of infecting a human. Obviously that isn't the case with human milk.

i'd have to tour the collection conditions for ... science

It would make more sense than consuming animal milk and could be a good revenue source for mothers

Eh, not really. It's nice in small amounts, but it isn't tasty enough to merit drinking a whole glass.

Yes. I don't like supporting supermarkets but this would make buying it so much easier that I'd make an exception.

Might get it once just to try but I don't drink milk in general so I don't really need it.

Depends on whose milk it is

I don't even buy cow milk