Ethicists do puzzle me sometimes. I've written about these sorts of cases before. Compare three scenarios:
1) The status quo: some people are desperately poor, and will remain that way.
2) Allow voluntary exchanges: some of those desperately poor people will choose to do things to improve their lot. (They might not especially wish to do those things, but they wish to remain desperately poor even less.)
3) Redistribution: provide a basic income or the like, to ensure that nobody is desperately poor in the first place.
Now, I think that option #3 is far and away the best. No-one should be so poor as to find exploitation preferable to the status quo. It's unconscionable. But it's also reality, at least for the moment. And given how awful the status quo is for them, we should surely allow them every opportunity to improve their lot. That is, #2 -- whilst unfortunate -- is a hell of a lot better than #1. So why would anyone defend the status quo, and seek to prevent the "exploitation" that's one of the few opportunities for these people to improve their situation? What's so damn ethical about keeping them miserably poor?
As a general rule, the way to respect another person is to let them decide. So think about it. Would poor women want the option to sell their eggs for a decent amount of money? I can't be sure, of course -- it may create new risks of coercion -- but I imagine most would want the option. (In a real democracy, someone would actually ask them.) So it would be awfully paternalistic to deny this to them, only to claim that you're doing so for their own sake!