Jian Yang's Barbie doll fixation began at age 13 when he bought the "Great Shape" model.

Now the avid collector owns more than 6,000 of the world's most famous doll.

SOUNDBITE: Jian Yang, doll collector, saying (English):

"Crazy obsession mainly. I buy one, I try to complete the series. I like fashion, I must admit, I like pop culture, I like celebrities, I like that kind of stuff."

The self-described "toy nerd" says his collection has cost him almost $400,000 U.S. dollars over the past 20 years.

Yang also has around 3,000 other dolls - he says Barbie's relevance is waning as more ghoulish toys become popular.

But he still has a soft spot for his rarest Barbie.

SOUNDBITE: Jian Yang, doll collector, saying (English):

"She's a 'Comme des Garcons' Barbie. So, 'Comme des garcons' is one of my favorite designers, and she's the rarest because even the collectors don't know about her. She's designed directly by Rei Kawakubo."

And when Yang's crammed cupboards fill up ... He jokes that he'll buy his neighbor's house.