Why are DVDs of zero-budget movies so expensive?

Nollywood.

I've seen companies online that say they're produce and package your DVD for surprisingly little money. One was $1.80 a copy for 100 copies.

I've never done it so I don't know what the issues are, but why are DVD's of zero budget movies so expensive? There aren't a lot of reviews of these things, there are no stars, in most cases you've never heard of any of the people involved. You're being asked to pay $30 for a movie sight unseen with the assumption that you're going to want to watch it again and again. They're usually dramas. If they were exploitation films, at least they could tell you objectively what you'd see. 

I wrote here long ago about a guy in England. He filmed an action movie using local hooligans as actors, then arranged to have DVDs of the movie sold in local shops for the equivalent of $5 each. It was cheap enough that people could buy them on impulse and it meant no one would bother to bootleg it. The movie was terrible, but the guy made a over twenty thousand dollars from it.

Nigeria has a thriving movie industry all off the sale of DVDs for a couple of dollars each.

There are probably good reasons the DVDs are so expensive. In most cases, you're not going to have the things in grocery stores. People don't buy them on impulse. Paying $5 for a movie you're not interested in is no bargain, so price may not have much affect on sales. A higher price might make people assume it's a better movie. Paying more might even make them like it better since they'd have to psychologically justify having blown thirty bucks on it.

There are writers making pretty good money selling their self-published novels on Kindle for less than a buck. You think guys with video cameras could pull off something similar?