In much of the human history aristocrats didn't breast feed at all, the babies were given to a wet nurse - a servant that had another baby and who breast feed the aristocrat baby.
I think that with the financial gap between rich and poor becoming larger all the time, we'll probably see more of this happening, sort of a contemporary take on the wet nurse thing...
I think that there's nothing wrong with it, as a business opportunity or a charity. A lot of women can't breast feed or don't want to and would love the accept this service.