Doesn't that allow an arbitrage situation, where you can buy Zimbabwe dollars through official channels and then sell them on E-bay for more than they cost you? Or maybe the "official" exchange rate is depressed through shortages and risk in completing the transaction.
I think supply/demand may get in the way: not that many people need zimbabwean dollars, just some collectors and those who seek them for novelty value. Market will become saturated pretty quickly.
