Would you buy or sell your breastmilk here? http://www.onlythebreast.com/ - It's like Craigslist, but solely for breastmilk!
From what I can see, it's all based on trust - I don't think there's a screening process in place for the breastmilk sold here... but people are selling their milk for $1.50-$2 an ounce!