Judging from engine deliveries, I'd think 30 prototypes and perhaps a slightly higher number of production aircraft. What I find interesting is comments that the J10 is a transitional model for ongoing development and China's methodology of using technology developed by others. There's no way any country will ever recover development costs from internally funded defense projects, which is going to make Chinese aircraft very competitive in the world market.
China's Fighters - Chengdu J-10