Strawberry Milk Tea

Robin's Egg

A native of Japan, Robin's Egg's customized dolls sell for high prices on Yahoo Japan Auctions. Although her site is entirely in Japanese, it is relatively easy to navigate.

Avvelenato

Profiled in Haute Doll magazine and Orbryarium, An Angel's Guide to Asian Ball Joint Dolls, her modified and painted doll heads sell for thousands of dollars on Yahoo Japan Auctions. Her face up of a Volks SD13 Souji Okita head sold for $5000 recently

There are many, many design houses just for dolls. Here is just a sampling of the most famous:

Dollheart

A Chinese based company, they design clothing sets for yo/tiny, mini, and standard sized dolls.

Mio

Another Space

Based out of Korea, this company designs for yo/tiny, mini, and standard sized dolls. Items can be purchased directly through their website or through Dollmore.