A photo of dong notes with "special" serial number posted on a seller's website
A 10,000 dong note can be sold for 400 times its value in Ho Chi Minh City if its serial number is formed by the repetition of one single number.
This business is run mostly by city college students, Doanh Nhan newspaper reported.
Nguyen Van Linh, a third-year student, said he buys notes that have a number repeated for VND2.5-2.7 million (US$120-130) and sells them for VND3-4 million. Rich people are willing to pay even more, he said.
The VND10,000 note is very popular since it has a lot of red, the color associated with good fortune lucky.
He usually makes a 30-50 percent profit.
Other popular bills are those in which "lucky" numbers like "9" and "8" are repeated.
The Chinese loanword for "8" rhymes with "prosper" and the one for "6" rhymes with "luck."
Notes with numbers that make up a birthday or anniversary date are also snapped up.
Linh has been collecting old and unusual bills from Vietnam and other countries for four years now, and opened a shop to sell them two years ago.
Another seller, Tuan, also a third-year student, has been collecting bills for 10 years and selling them for more than four years.
Tuan said he is well-known in the business since he advertises online.
"Some customers were far away. They read about me on the Internet and called to order for the notes, no matter what price.
"Many of the customers do it for the joy of giving these special notes to their bosses or lovers as gifts," he said.
Tuan said there are now more than 20 shops in the country doing the business, mostly students who know each other and sometimes buy from the others to serve their customers.
But with more and more people becoming notaphilists -- as the hobby is called -- it is becoming harder to find unusual notes, he said.
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