You are probably familiar with eBay - a similar site exists in China called Taobao 淘宝 (http://www.taobao.com). On Taobao you can pretty much find anything you can imagine at very competitive prices.
Buying stuff on Taobao
First you do a search for the item you want to buy. For example: If you are looking for this brand of cosmetics, i.e. BB SKIN79 (I was told is a popular Korean brand).... You will get the below pages...
Here, there are few things you will need to take note. If you see the following logo...
This usually means it has been verified as a genuine brand (not fake). Also, it is available on Hitao (嗨淘）, a subsidiary shop from TaoBao.Com that guarantee quality and branding. Usually, it is safe to buy from these sites.
The next thing you could do is to SORT it by selling quantity within the last few days. i.e.
You can select to sort using price, credibility, and selling quantities. In our example below, we sorted with selling quantities. You can see that this company actually sold 7095 deals within the last few days. So, a lot of people buying it. So, what you do, is you click on the product and take a look if there is a lot of people complaint or comment on it. Because there is no brand guarantee logo there.
So, it is always based on these few things to determine if the goods are good or bad, is it fake, and so on. You can check even on the selling records just to make sure that there is no fake transactions, etc. But my advise is always buy from the brand guaranteed item, regardless if the price is higher a bit.