It's about here on Google Maps.
Inside the first ring road. I can't actually remember the address, I could find it again if I was there. Chouyangmen is the nearest station on the 2 line.
Sorry I can't do any better than that.
This is the big electronics mall that my Beijing guide app was referring to.
To access the market area by public transport take the subway to Wudaokou Station or tell any taxi driver that you wish to go to Zhong Guan Cun, Ke Mao Dashi.