I've found that the price on books fluctuates up & down a bit from book to book but most mini-series seem to be a bit more expensive then your regular monthly title.
I've seen where the 1st couple issues of a new series are priced cheap to get people into reading the series & then by the 4th or 5th issues the price goes up to it's "regular" price which is a dollar to a dollar & half more expensive.
Also with comics being as expensive as they are people are finding that they are reading less & less. But I've been reading less & less because I'm find more & more stuff I just don't want to read anymore.