"Should be consistent" and "is consistent" are two different things, though. I've got my book distributed on Smashwords, B&N and Amazon for the same list price ($2.99), but Amazon has discounted it to 50% of their own volition*. This is only mildly aggravating to me, but it's surely within their rights to do so... just as it's within my rights to offer a Smashwords coupon that undercuts Amazon's own price.
Nyah!
Officially, the price -- as set by me -- is consistent. What happens on the retailer's site is out of my control unless I decide to re-price down to the minimum**.
EDIT to add: and Amazon has since bumped it back up to my list price, but showing it as a discount vs. the POD version.
* And surely as per the user agreement terms, in the clause right after the bit where I hand over my first born.
** Interestingly, I had priced an earlier version at $1.49, and then upped it when I put the final polish on it. So, Amazon has returned the price to its origin point, AND made it theoretically more appealing to readers since it's 50% off list. And I have sold a few since repriced. Psychology at work?