The charm of Barbie dolls never fades. Even at this era, when young girls go to play videogames or roleplay adult acts that they see on TV, Barbie dolls are still in high demand online. Collectible Barbie dolls are great for auction ecommerce sites such as eBay because people can buy, sell, or trade their collectibles for a good profit.
The only fault I find at banking on collectible Barbie dolls online is that sometimes they are only bought or sold in certain territories such as Asia or Europe. Real collectors would go all the way to asking for help from a friend who lives in another continent to be able to buy the dolls. Any chance however, you might spot a good item on an ecommerce site so you should keep looking.
Vintage Barbie dolls are my favorites. Though I don't sell them, I've done a good deal of collection when I was a kid. I didn't put up my own store to auction it though, because I can easily do it on eBay and Amazon. I've seen a lot of good ecommerce sites specializing on trading Barbie dolls also. It doesn't take a genius to build one, but it takes insight to realize that these holiday season, you might just make good money off selling these girly toys online!