I have mixed thoughts and feelings regarding surrogacy.
That said, while you cannot sell your own body or body parts you can donate your organs, blood and bone marrow, eggs, sperm... There are also medical risks associated with donation of some body parts and fluids while alive. Some people still chose to do so (reasonably freely), and it is usually celebrated and not condemned as exploitation, provided only medical expenses are covered and nothing is being bought.
Equally, one cannot sell a child who has been born (I can see how some could see surrogacy as also buying a child), but you can give up a child to another family via adoption.
I don't like the sort of surrogacy where rich westerners pay poor women from another country to carry a child, because of the arguments already made around 'choice'. There is a power and economic disparity.
However, surrogacy where the economic situation is more equal, especially something done for those known to the surrogate, I do not see a problem with. I think a woman should be permitted to create and birth a child for another if she wishes, say for close friends, in the same way she could give blood or a kidney to another. If one of my female cousins required such support, I would gladly do so, knowing the risks, out of love (though I suppose love is not always a choice, either, but in a rather different way than when money is exchanged). I'd also do it gladly for a gay couple I know who are as close to me as family. I would expect and want nothing in return. Again, an act of love.
But I do not think such services should be sold, in the same way body parts should not be sold, because that feels wrong in all sorts of ways already discussed.
I respect entirely others views either way, as I do not think it a simple matter, though I expect in a relatively, even frighteningly, short time it will be possible to grow babies in bags (artificial wombs are already being developed for premature babies), and the whole issue will become outdated. Perhaps, future humans will one day be amazed anyone risked their lives and health in such a way before hand, as pregnancy and childbirth?
Regardless, I find the story is extremely tragic.