Here is the place I like best.
http://www.amazon.cn/It is affiliated with amazon.com and has the same look and feel except everything is in Chinese. But you can find just about anything there and once you set up your payment account, purchasing and paying is very quick.
They have a distribution center here in Guangzhou so everything for me arrives the next day. And it is delivered right to your door. The prices are better that the other merchants around here by about 10-20 percent.
Here a some others but I wouldnt trust them as far as I could throw them.
http://www.paipai.com/?pps=etg.0_11178_9_0&outInfo=&PTAG=20097.1.1http://www.aliexpress.com/ (great prices but they will not ship to mainland china.)
gome is a retailer of appliances and electrical toys but I cant find their online store anymore. (maybe because their shares have dropped 20% and the owner is now in Jail)
Suning Appliance is a major competitor of gome.
Best buy has a partner here in China Five Star Appliance Co., Ltd. I dont know if they sell online or not.
And of course what would China be without Walmart? They have an online sams store.
http://www.samsclub.cn/sams/homepage.jsp