I wasn't sure how much cheaper it is. All I know is that crucial has an App to check the compatibility. So it should work.
Interesting Fact, on the new Macbooks, a 4GB Ram upgrade costs £80.01
Double the price of the RAM at crucial. Not sure why Apple charges the extra 0.01p. Although, looking at the price of the Apple Remote, its not surprising. Wonder why the remote ain't free anymore.
Anyways. Hope you get some good cheap ram.