So here's an interesting article about noitaminA (ノイタミナ) and DVD sales. noitaminA is a programming block that's intended for anime that appeals to audiences beyond the typical shounen/seinen fans. The shows that run in this block are usually of excellent quality. They've had some pretty big shows run, like Honey and Clover and Nodame Cantabile. This season, they're running Eden of the East.
What's interesting is that even though a lot of the shows receive very high ratings, those ratings don't translate to DVD sales. I've linked to the top DVD sales for the week of March 30 - April 5 below. It turns out that running ads doesn't make enough to recover the costs of production. Of the shows they've run, only Honey and Clover, Paradise Kiss, and Jyu Oh Sei were available in North America.
It's unfortunate, because a lot of these shows are really good.
Links: MAL news thread, Japanese DVD sales March 30 - April 5