The publishers in question are members of a free economy, and they don't need to justify their prices to anybody. They will certainly take production costs into account, but presumably they are interested in higher profit margins if such are available. Fair enough.
It could be argued that higher prices, when it comes to electronic formats, lead to more paper purchases, piracy, less sales, etc. True or not, it must be admitted we have an interest in the outcome, so whatever.
What bothers me personally is when it seems publishers aren't paying attention; when it seems they are pricing irrationally, and if someone would just take a look everyone--publishers and readers both--would be happier.