iBookstore mark-up

I have just discovered that my novel costs an extra dollar throught the iBooks boostore. It is listed there at $3.99.
Grab it there, if you like. I have used the store a few times and find it reasonably simple.
But I was surprised, since it is listed at $2.99 elsewhere, including Smashwords, where the links to the side will take you.
I have no illusions needing disabusing; I know I am an unknown, self-published hack of a writer. To me, 3.99 is too high a price point. A buck cheaper may be, too. But if you'd check out my book fot $2.99 but not $3.99, check around. You might just avoid the iBooks markup!
Love saving you $$!