Allow paying organ donors (or their estates), and shortages will be eliminated or drastically reduced. Economics 101.
I understand and agree to a point. Post-mortem payments to estates are cool; it will encourage more people to be organ donors. Not to keen on just deregulating the whole thing, though; I'd be worried about people getting kidnapped and killed for their $20k kidneys.
You said "paying donors," but I gather you mean paying recipients. Economics 101? Sure, Satanomics.
Allow paying recipients and you've created a market. Economics 101.
There is also the effect of the supply-side to be considered in stimulating demand.
That is why some arenas are to be protected from what are normally considered the principles of "Economics 101."
That is why the principles of production, distribution, and consumption of goods and services (otherwise known as "economics") is to be subject to moral restraints or else will foster the production, distribution, and consumption what should never be.