There is a website called collectorsconnection.com. It lists a bunch once you clip on the first letter of what you are looking for. So you would click on D for dolls. It could possibly be A for antique dolls, but I doubt it. Good Luck.
Barbiecollector.com for new collectible Barbies, and Ebay.com for older collectible Barbies
The best places are doll shows and the Internet.Besides the Internet, there are: garage sales and flea...
I am actually about to sell a some of my Collectors Choice by DanDee dolls very soon. I have some limited edition ones also. You can contact me at Aubbawb@aol.com