Not sure if they are expensives.. but the vast majority of the albums from "
Absord Music Japan" are somewhat rare, with a few ones that are hardly to be seen anywhere, like these A-Train albums.. and for some games you probably never heard of:
Pinocchia no Miru Yume ?
Ichigeki: Hagane no Hito ?
Kyabate Bakaichidai ?
Though i am agree with Teioh, rarity and price are different.
Price does not indicate the rarity to me.