Humm, deep insight on emotions and the feelings of the surrogate mother. Just like someone who kills or steals, the first time of being a surrogate mother might attract a whole lot of emotions, but what happens the second, third, and fourth time and so on, they begin to loose emotions and see it as "not a big deal".
How ever for the process of surrogacy is already a choice, no one forces a woman to carry their pregnancy for nine months she chose to because she's willing to do it for the rewards. Someone's problem is someone elses business, that's life in general.
The expecting parents do not see it has business, they are only willing to pay because they probably do not have a choice, or even they do not have the time. How ever for the surrogate, she sees it has business because of the benefits. So I really don't think it's not fair on the surrogate mothers as long has she wasn't forced against her choice