According to Mainichi, cosplay clothing maker COSPA released the yearly sales ranking for 2010.

*1, Toaru Majutsu no Index Tokiwadai Junior High (Pictures)
*2, K-ON!! Sakuragaoka High (Pictures)
*3, Amagami Kibito High (Pictures)
*4, Mashiroiro Symphony Yuihime Girl's Academy (Pictures)
*5, Mahou Shoujo Lyrical Nanoha The Movie 1st Seisho Elementary School (Pictures)
*6, Suzumiya Haruhi no Yuuutsu Kita High (Pictures)
*7, Tokimeki Memorial 4 Kirameki High (Pictures)
*8, Evangelion: 2.0 You Can (Not) Advance Tokyo III Daiichi Junior High (Pictures)
*9, Fortune Arterial Shuchikan Academy (Pictures)
10, Koi to Senkyo to Chocolate (game) Takafuji Academy (Pictures)

Source: Mainichi