I think you're getting a pretty good deal. This past winter AA and JL offered a JFK-TPE r/t in J for $2300, which was a great deal
(JL) Business JFK-TPE return for $2300
TPE tends to attract some of the better pricing, and going onwards TPE-SIN is cheap. This was about as low as it will get for a carrier like JL, but no guarantee we'll see a similar sale in the future. As others have mentioned, mainland China carriers may be lower at times, but generally you'll get what you pay for.