I'm sure some people have seen this before, but I found this post on
sofaspud.org really interesting:

"Since Best Buy also sells anime DVDs, I was able to look up the
wholesale cost of them. If you've ever wondered about how much a DVD
actually costs to a retailer, look no further. Before working at Best Buy
I looked all over for this kind of information and never could find it.
Use this information well. 

All prices are based upon the wholesale cost of a DVD with a $29.99 MSRP
(Manufacturer's suggested Retail Price). However, markup percentages
apply for any company's product regardless of MSRP. 

ADV - $14.51 (51.6% Markup) 
TokyoPOP - $15.12 (49.6% Markup) 
Manga Entertainment - $15.41 (48.6% Markup) 
Pioneer/Bandai/Viz - $18.73 (37.5% Markup) 

Depending on the agreement a vendor has with a distributor, there can up
to a +4% variance on these prices. 

When shopping online, try to get a deal as close to the above prices as
possible. When calculating for things like boxed sets, take the MSRP for
the set and subtract it by the percentages above. Example: To calculate a
fair price for the Evangelion Boxed Set ($169.99 MSRP) you subtract 51.6%
from $169.99, which gives you a total of $82.27. 

Use this information to help keep money in your pocket rather than the
retailers."