Most Lolita fashions come from direct from Japan but there are plenty of gothic lolita shops online that sell all kinds of lolita fashions.
Anime Festival & Fashion Show in New York http://www.babyssb.co.jp/ featuring Baby The Stars Shine Bright Gothic Lolita Line.
Angelic Pretty is a sweet lolita style website. http://www.jp-stores.com/welt/shop/we60157/
http://www.cosmates.jp/ mostly a Japanese costume shop sells all kinds of gothic lolita dresses.
If you are looking for elegent gothic lolita fashion visit http://www.metamorphose.gr.jp/english/
Candy Violet Lolita is an american company that has plus sizes http://www.candyviolet.com/