So as a far as PLAAF is concerned, J-10 may be cheaper than FC-1.
So there is currently no advantage of going for FC-1.
I respectfully doubt that this is the case. J-10 is a larger and more sophisticated aircraft, it follows that it's manufacturing cost is also higher. Cost of avionics these aircraft field are also different. For example, @Munir mentioned this cross-feeding of technology between aircraft - and though JF-17's KLJ-07 and J-10A's KLJ-10 radar have the same design heritage(KLJ-07 essentially being a smaller KLJ-10 with a smaller sender/reciever dish and lower wattage), the difference in size, complexity, power output, is bound to result in a cost-difference. These radars, for example, are bound to differ in costs, just like they differ in performance.
Difference in performance is not enormously large, as both these radars are integrated with the same frontline weaponry(same SD-10A/B BVR, PL-5E WVR, C-802/803 AShM, etc) and PLAAF can get something that may not match up to J-10's performance, but also not so far behind either. The difference in combat range&ferry range(two things that matter alot to China which has large areas to cover) are not that large either. As China's economy also experiences ripples of this global economic meltdown that started in the west, and budgets are tightened, FC-1/J-9/JF-17 may become an appealing option with sufficient performance.
Rightnow, it's hard to make informed guesses. We've heard from official sources, which include CAC officials at Dubai, which say that PLAAF is still considering this prospect and might make a decision "very soon". We've also officially heard how, back in 2009,
. And the last semi-official thing to note - returning from the latest Zhuhai airshow, a senior PAF official mentioned at an interview on Sept 6, how JF-17's performance at Zhuhai met with alot of approval. J-10's Chengdu designers(same folks who designed JF-17) happily told the PAF team how, despite J-10 being a superior aircraft, JF-17's better demo made it seem like JF-17 was superior(J-10's demonstration was complicated by windy&stormy weather).