I'm just getting into the Twilight series, and the first book I bought was Twilight, for 9.99. -- but the second book in the series is 14.99 for some reason, then the ones after that go back to 9.99. Seems strange, but it's the same price at Amazon.
I'm also reading Jim Butcher, and I gor the first in his Dresden series for 6.99.
The prices don't seem bad overall.