Selling your organs out of desperation is pretty much as low as you can go for money. Maybe selling yourself for sex is lower, but you can argue that you're still physically all there after that. So the argument of preventing them sinking even lower is a non-issue. Selling your organs is right down there with the lowest.

> what is your solution?

The solution is for people to start supporting sciences to regrow organs from stem cells. That fixes 99% of the issues. Which brings up another point, say you legalize organ sales, and businesses become established, who do you think is going to be opposing regrowing organs? The businesses brokering the sale of organs. They're not going to want kill off their whole industry so everyone can get the organs they need directly.

In the long term, selling organs will create more problems and suffering than they'll solve. Let's face it, this is only an issue to rich people who are dying with 5-6 disposable figures. You don't see poor people begging legislators to let them sell their own organs, because deep down, they know that they never want it to come to that.