Its actually the job of a breast pump. Only pregnant ladies or those ladies who just gave birth is able to produce breast milk. I'd say this lady probably doesn't want to waste her milk and try to sell it. On the other hand, why don't she benefit her own baby, and instead she sell it.
But seriously, not all mums are able to breast feed. I've read in articles that some mums find it difficult to breast feed, its some physhcological issue. I've even heard of cases of new mum who don't have milk, their milk glands just can't produce milk. So this guy selling breast milk here probably is doing others a favour by selling breast milk to those who needs help.
Whether its real or not, i don't know la. I was not old enough to taste and understand how breast milk taste like. Perhaps any father's here can testify how much difference is breast milk compared to cow's.