UNIVERSITY student Jessie Liu is a walking encyclopedia when it comes to purchasing low-cost foreign cosmetics on the Internet.

Well-known brands are much cheaper overseas and many Chinese women buy them online. Some buy them abroad when they travel, bring them home to sell and make a killing. Health products, nutritional supplements, fashion and accessories are popular.

Liu, a 20-year-old student from Shanghai University, has collected more than 400 Website addresses in her browser's "Favorites" folder, all for purchasing from overseas for herself.

But Liu has been on high alert since February when she discovered online that she might have been buying expired or fake products all along.

"It's just money," she says, "but I'm really worried about all the cosmetics I have bought and used. What would happen to my face if they are expired or fakes?"

Liu and her friends got worried after discovering a hot online post titled "Top Credit Online Stores Are Found Selling Fakes." At first she ignored it, saying "these kinds of rumors are posted online all the time, with no evidence to back them up."

But the anonymous post author explains the differences in details and posted comparative pictures of the genuine and fake packaged products.

The difference is often in the fine print, maybe just a letter, in the often-ignored bottom line of the content description.

The post generated a firestorm: More than 300 responses in 10 hours, 6,000 within a week, then up to 10,000 and still going.

The author also cites more than 30 popular online stores that allegedly sold fake or expired fancy cosmetics, including Taobao, a Chinese version of eBay.

All the stores are highly rated by buyers and sellers who post thousands of positive comments. Many have a satisfaction rate of 99 percent.

The author's claims have not been verified, but the concern appears to be timely.

After the posting appeared, generating an uproar, many online stores, including Taobao, asked sellers to remove cosmetics and medicine, two of the most sought-after products, pending investigation and verification.

Some cosmetics and health products have been restored to their online stores.

Fashion editor Momo Huang of online women's magazine, White Collars Fashion, cautions against buying cosmetics online.

"You should be careful about what you put on your face," she tells Shanghai Daily, "and it's difficult to verify that online cosmetics are genuine."

Many people who responded to the original posting reveal they have bought cosmetics from those online stores and never suspected a problem.

Like Liu, many were torn between denial and concerns about the products.

Some were furious - there was so much verbal violence from the ladies that the forum had to remove the comments.

Dai gou, which stands for "buying on someone else's behalf," is not new in China. In the 1980s, people asked friends or relatives going to Shanghai on business to bring back some fashionable accessories that were not available elsewhere.

In the 1990s, the destination became Hong Kong, as it became easier to go to the "shopping heaven," where prices for cosmetics, electronics and luxury brands are much cheaper.

As the Internet developed, people didn't need to ask travelers to shop on their behalf. Online shopping became popular.

Taobao has a special category for purchasing from overseas.

Website statistics show the revenue in this category rose to 520 million yuan (US$76.1 million) in the first quarter of 2008 from 9 million in the same period of 2007, an increase of 481 percent.

The global financial crisis has given a big boost to the online business since last June.

Many luxury brands went on sale and Chinese buyers snapped up bargains as the yuan appreciated strongly against the euro, British pound, Australian dollar, US dollar and Japanese yen, among other currencies.

The most popular products from overseas are designer clothes and accessories, cosmetics and health products (such as vitamins, supplements and diet pills).

The most popular destinations include Japan, South Korea, America, Australia and France.

"Most Western brands have always been much more expensive on the Chinese mainland, because of tariff and additional costs on regional sales agents," says editor Huang.

"Some brands like Coach or Nine West are not that costly in the West, but they are sold at much higher prices here," she adds.

She has written a series of articles and posted guidelines on her magazine's Website about how to choose online stores selling overseas products.

"The price has dropped more than half for a lot of well-known brands like LV, Coach and Shiseido, both because of discounts and depreciation of other currencies in the financial crisis," says Huang.

Shopping can be quite tricky for new buyers since hundreds of search results pop up for popular brands.

On the other hand, many rookies jump right into sales "to make some extra money in the bad times," like 28-year-old marketing manager Linda Xu who works in Seoul.

"Some South Korean cosmetics and fashions are very popular in China, probably because of the Korean TV dramas and the low prices," says Xu via telephone.

Xu charges 10 percent of the product price for handling and transport, according to an unwritten industry rule.

It can be up to 20 percent, depending on the product.

It is still 20 to 30 percent cheaper than buying on the Chinese mainland, however.

This often means a saving of a couple hundred yuan or more than 1,000 yuan on luxury brands or cosmetics.

Xu goes shopping three to four times a week in Seoul and makes around 4,000 yuan every month - not bad, she says, for a part-time job that doesn't require a lot of investment or skills.

Her income peaked at 9,000 yuan last November when Korean won dropped rapidly.

Philippe Guo, studying at the University of Chicago for a master's degree, is another rookie purchaser.

He works for a small online store selling clothes and home appliances that compares prices of the same product in different areas.

Guo is paid on commission. He usually goes shopping twice a week and makes about 2,500 yuan every month.

His workload and monthly income have both tripled since last September.

Tips from fashion editor Momo Huang

1. It's better not to buy cosmetics online. It's difficult to verify whether they are genuine, and you should be careful about what you put on your face.

2. Choose a relatively well-known and large Website and research well before ordering, particularly for small private stores. Read users' comments carefully.

3. Confirm your requirement with the seller carefully to ensure you get the right products.

4. Ask sellers to provide shopping receipts, invoices and the addresses and contact numbers for stores where they purchased.

5. Save all online communications with the seller.

6. Be cautious if the online store sells everything, particularly when it's a small private one. The store owner is less likely to have access to so many categories of products made or sold in many different areas. The sellers who stick to a few categories in one country is more likely to be genuine.

7. Don't trust a ridiculously low price (less than half). If it sounds too good to be true, it probably is. It's impossible for sellers to get such a cheap sale.