Check this article out:
http://webcache.googleusercontent.com/search?q=cache:qgniSv8RtZIJ:www.echinacities.com/news/25000-Foreigners-in-Chengdu-16-of-Shanghai-and-18-of-Beijing+&cd=1&hl=en&ct=clnk&gl=us
25,000 expats are said to live in Chengdu. Didn’t get the original source for that number though…
On a side note, how much I hope I had found this forum before I left Chengdu this winter….