Regarding pricing, it is usually what is out of stock and had a rather limited print run is going up in price.
Like if there's a Anime TV series splitted into several volumes, usually the last ones can be pretty pricy. Or if there's a collection box, the whole box is expensive. Releasing a TV series that spans more than half a year of episodes (20+) is usually a not really fortunate deal for distributors in markets outside of Japan. They have a hard time selling all of the volumes in English speaking countries, and for small markets like Germany, the local distributors are even facing more difficuilties. Even seemingly safe bets such as Dragon Ball, Sailor Moon and Naruto aren't that easy to sell, thanks to them being rather long series. Which is unfortunate, since I would like to see a re-issue of the Kimagure Orange Road releases.
Single movies or releases that span no more than two or three volumes seems to have been less affected by rising prices, they are rather going down over time and can be had pretty cheap. My guess is that distributors have an easier time getting a large print run of these to sell successfully.
Another factor is that subbed-only releases are harder to sell to the mass market. The average Joe doesn't walk into a store for a subbed-only anime, he rather takes something that includes a dub, regardless if that dub is good or bad. Subtitles and the original Japanese language track are an afterthought for him, even if that feature is more important for people like us.
I keep in mind that from 2008 to 2010, many distributors of Anime in the US, UK and Germany went bankrupt or defunct. Like ADV Films, OVA Films, Central Park Media, Panini Video and SPV. I bet you guys can name a few more, don't you?
Some releases before that time must have gotten such oversized print runs, that you'll find them for cheap as chips still today, ten years later. While other releases seem to have gone straight for the opposite.
