Just like shoes or shirts, it appears that the price of an Afghan vote was determined by demand and supply. For the Afghan election, according to the NY Times, the 2500 candidates were the buyers. The sellers were the voters. The price–the point where quantity demanded and quantity supplied intersected–varied. The average income of the local voting population influenced the supply curve.
As a consistent reader of marginalrevolution.com, I was reminded of their “markets in everything” link that appears occasionally. In addition to citing Afghan votes, they have also linked to “nothing” having a price on eBay, and a proposed market in high speed driving in Nevada.
The Economics Lesson
Through a demand and supply graph with price the Y-axis, quantity the X-axis, a downward sloping demand curve, and an upward sloping supply curve, we can picture the price of an Afghan vote. A supply schedule would list all of the different prices that voters were willing and able to accept. On the demand side, the amounts that candidates were willing and able to spend would be listed. Hypothetically speaking, the graphs would differ from one locale to another.