Doctors have often said a mother's breast milk is better for her baby because it boosts immunity and even intelligence.

Yet, not all women are able to breast feed -- prompting some to buy breast milk online from other women who can.

"It definitely did seem weird to me, but I knew I was helping a family in need," said Kamilla Vainshotk, who sells her breast milk on the Internet. Their child wasn't responding well to formula, was having a lot of tummy aches and spit-ups."

"So I figured if I was able to help this child with breast milk because their mother wasn't able to, then I might as well help them out," she continued.

The Food and Drug Administration does not recommend buying breast milk on the open market, but instead through approved milk banks.

A month's supply can cost anywhere from $300 up to $1,200.