As buying power varies from place to place we see different effects on commodities. Drugs are a particularly useful example, as they are prone to intellectual piracy. So in a place with relatively low purchasing power, a two tier economy can exist: that of the legitimate branded drug and it's pirated version.
It can provide interesting insight into the economy when we look at a specific sub-set of the drug market, the so-called erectile dysfunction market. The drugs are made to satisfy an issue which could be considered more social than medical.
The erectile dysfunction market is interesting because, economically speaking, the drug is a luxury product - as opposed to malaria tablets, for example. So how the market, both formal prix des médicaments d\'ordonnance pour l\'impuissance masculine and informal (prices of their knock-offs) versions, operates is very interesting.
As anyone who has seen a pirated DVD will tell you, the knock-off drugs have a quality control issue. So, how the informal erectile dysfunction market prices this risk is also interesting - and in established informal markets there are likely tiering of pricing around the understood quality and effectiveness of the knock-off "brands".
Contrast this to established economies where there is little in the way of an informal market. The relative earning power is higher, so therefore the consumers are likely to buy the standard brand drugs.
