anyone know a place to buy second hand stuff, want to buy nice computer chair , new one is about 800 

 。。。

Hahahahaha ... but what's your budget?

I found some on Taobao.com based in Beijing, so I hope you can read Chinese, or have someone to help you with ...

http://item.taobao.com/item.htm?id=17244416810

http://item.taobao.com/item.htm?id=15677089986

http://item.taobao.com/item.htm?id=10460555812

http://item.taobao.com/item.htm?id=15559830962

http://item.taobao.com/item.htm?id=19396584040

http://item.taobao.com/item.htm?id=15290189858

 。。。

(continued) ... and there are also many pages of (supposedly) brand new ones as advertised on Taobao.com... I have given you here only a few of them ...

http://item.taobao.com/item.htm?id=12597632949

http://item.taobao.com/item.htm?id=15722057007

http://item.taobao.com/item.htm?id=5663431382

http://item.taobao.com/item.htm?id=1535564902

... if you know Chinese, or have someone with you that do, just search for 北京 电脑椅, and you should find many pages of it ...

  ...

(continued) ... somehow, Taobao (or otherwise) has planted a cookie of sort, and "suggested" me to view this page:

http://tao.etao.com/auction?keyword=%D6%B0%D4%B1%D2%CE%2F%B5%E7%C4%D4%D2%CE&catid=50001400&refpid=tt...

... some of these are below 200 and are outside Beijing, but have free delivery ... enjoy your shopping :)  

 ...

(continued) ... probably some form of courier or logistic service?