Thank you
These kinds of dolls are more likely known as "Asian Ball Jointed Dolls" because of the unique look, compared to ordinary Ball Jointed Dolls much like Barbie and such.
Now there are various websites/companies that sell ABJDs. Specifically, mine was bought from
LUTS. But you can just research other websites about BJDs here in
wikipedia.
Hope this helps. Thank you again
~eRu~