The problem is more to do with pool of customers and alliances - the countries that Pakistan (JF-17 is more of a Pakistan thing than China - it is the PAC that's pushing it hard for export) can safely sell JF-17 to are few. Ones that can afford it are even fewer.
Pakistan naturally wants to sell it to its traditional allies, which are mostly muslim countries. And those that are rich enough to be able to afford it usually opted for American or European because of "alliances" (Saudi for example, more american than european due to political alliances) and price range (if you are rich enough to buy Farrari and already got one and thinking of buying a second car, you won't be thinking of buying a Toyota Yaris).
A look at the past interested buyers :Algeria, Argentina, Bangladesh, Myanmar, Egypt, Iran, Lebanon, Malaysia, Morocco, Nigeria, Sri Lanka, and Uruguay; half of them are just too poor to be able to afford it. and JF-17 is not cheap enough like the old Migs (J-5, J-6, J-7) that China sold heaps to the third world countries mostly in Africa.
I think JF-17 has to be price differently and target differently. It is for countries that has a sizable economy that just wants a cheaper alternative for their lower-tier fighters for their "Hi-Lo" mix. And most importantly, countries that are not aligned to or influenced by the US/European politics. I think Brazil and South Africa are two possible customers that Pakistan should aggressively targeting for.
South Africa for example, has only 26 Saab Gripen for ALL their combat squadrons - that's really low for a large country like South Africa. Brazil on the other hand has 47 AMX, 43 F-5, and 36 Gripen on order. Basically the JF-17 has to compete with the Gripen. I think price performance wise JF-17 is highly competitive.
Another thing I think that's limiting the sales is the political influences but that may change as China's Silk Road Initiative may open up more doors for Pakistan and China to export JF-17 to from traditionally Russian influenced east european and central asian countries as they become more accepting to Chinese products. Having say that though, JF-17 has to get its own indigenous engine for this to work or it will still get blocked by the Russians (because JF-17 still use Russian engines until WS-13 becomes operational) when it starts to compete with their lower tier fighters on the market.