Difference in DVD Versions

I wonder what's the difference between the Japan version anime DVDs and the US version anime DVDs.

Girls Bravo DVD 1 Japan Version	Girls Bravo DVD 1 US Version
Japanese Audio	English & Japanese Audio
Japan Version	US Version
same # of episodes
same length of video
Costs US$54.99	Costs US$24.98

If I was to judge the features, I would get the US version but it makes me wonder why is the japanese version of the anime dvd more costly (twice the cost)?

Note: Data taken from Girls bravo DVD 1.