A potential homebuyer checks realty brochures at a property expo in Shanghai.[Photo?Provided to China Daily]

Nine 12-square-meter apartments were sold for 880,000 yuan ($140,000) each in Shenzhen, South China's Guangdong province, on Sept 24, the day they went on sale. Buyers were apparently waiting for two months for the "pigeon hole" apartments. Beijing Youth Daily commented on Monday:

That the apartments were sold at such a high price shows the property market in first-tier cities like Shenzhen is getting hotter. In terms of per sq m, the "pigeon holes" were expensive. But they had a strong selling point: they cost less than a normal apartment that would cover more than 60 sq m.

The property market seems immune to the established economic theory that when the price of a product goes up its demand goes down. The higher the housing prices rise in first- and second-tier cities, the fiercer the competition gets. In contrast, property developers in many third- and fourth-tier cities are finding it hard to even maintain the current rate of demand.

Many people will buy the Shenzhen-style "pigeon holes" in first-tier cities simply because they cannot afford a bigger house. But if the property prices continue to rise sharply, where will all this end?