NCL is set to stop shipping opaque GBA colors in Japan.
According to The Magic Box, Nintendo has decided to unify GBA color selections by taking the opaque Japanese models off the market. TMB says this will take place "after April"...dunno if that means now or starting May 2002. Anyway, those solid purple import GBAs might be a collector's item before too long!
Also, thanks to Mikey for bringing this to our attention.