Given that the program has two separate voicebanks, Rin and Len Kagamine still sell for the same amount as Miku Hatsune; approximately $200 USD.
Rin and Len were first released December 27th with an ACT1 that was of terrible quality. Crypton quickly released an ACT2, and gave users who purchased ACT1 the new ACT free of charge. ACT2 is no longer sold.
Len is due to get 3 appends, Moody, Soft, and Power, December of 2010, and a possible english update, if Miku Hatsune's English update sells well.
Len has many squealing fangirls. We know that his proven 'biggest fangirl' goes by the name of 'Luna' or 'Krystal'.
He is most often paired with KAITO or Rin, as far as VOCALOID go, and is paired with Ichine Luna as far as UTAU go.
Despite popular belief, Len's name is spelt as it is on the box, 'Len Kagamine', not Ren. Rin and Len's names are puns on Right(Rin) and Left(Len). The spelling is important.
I just bought Rin and Len.
Len has a large fanbase of squealing fangirls and dies frequently in Vocaloid PVs. He is often paired with other male Vocaloids by the will of these fangirls.
There is a large debate among Vocaloid fans about whether Rin and Len are siblings or mirror reflections. This is rooted in the fact that in the actual Vocaloid program, Rin and Len come as a set and have the same voice actress, as well as the claim that the creator made an announcement that "Rin and Len are not twins, and are in fact mirror reflections". Also, their last name, "Kagamine" is translated as "Mirror-sound", as well as their names "Rin" and "Len" meaning "right" and "left".
Yeah, I actually just bought Rin and Len.