Asian males, the easiest way is to buy Barbie's DoTW (Dolls of The World): Japanese Ken.
For asian female, you can get any DoTW form asian countries. Such as: Korea, Japan, China. They also have several that fit the bill from the 80s to current.
I Can be... is a barbie play line. Just look for
I can be President, and they have an asian doll. I've seen her both at Toys R Us and Walmart.
You will find little to
no articulation with the dolls listed above. However you can rebody them. Women on
Fashionistas (you can get your "white girl" this way) and Ken on a
Harley Davidson Ken body (the only truly articulated male body available from Barbie - they have a semi-articulated male Fashionistas doll"Ryan" or "Ken").
If you use ebay, under dolls there is a category for barbie and you can find mix-lots sometimes or go specific to Nude Dolls and find them for lower prices than store-bought. Same with clothing, you'd have to just look around for what fits your "inspired" standards. ;]
Hope this helps.
ALSO: Ideals and inspiration, you'll find sometimes you can just mod the paint job on a "white doll."
http://www.flickr.com/groups/barbieasianfriends/