According to the CIA World Factbook the economy of the area administered by Turkish Cypriots has roughly 30% of the per capita GDP of the south. Economic growth tends to be volatile, given the north's relative isolation, bloated public sector, reliance on the Turkish lira, and small market size.
Exports, including citrus, dairy, potatoes and textiles, amount to $68.1 million (2007 est.) and imports, mainly commodities such as vehicles, fuel, cigarettes, food, minerals, chemicals, and machinery, amounts to $1.2 billion (2007 est.). I'm no economist, but this does not appear to be a sustainable economy.
Turkey accounts for 40% of export, and 60% of import, trade. Which countries account for the other significant trade, presumably illegal, which contributes to the economy of the occupied area?