I just upgraded to OS X Yosemite and as far as I recall the presentation Apple said that iWork is for free now as well? The reason I ask is because there is still a price in the App Store.
Or is just the update for owners free?
Yes & No.
It's free for recent Apple hardware purchasers - though irritatingly I can get it for free on my iPhone but not my Mac...
You can download the iWork 09 trial for free & App Store will then update it to the current version.
I'm not sure whether it's strictly legal or not, but I'm sure they could have shut it down years ago if they really didn't like it.
Go to Softpedia
Click on External Mirror 1
This will download iWork09Trial.
Open the dmg & run the installer.
Run any of the 3 apps, then check App Store for updates.
Edit : After the release of Yosemite, you can no longer update to the latest versions of these if you are still on Mavericks or below. They are now considered "Incompatible Updates". Same for Aperture, iMovie & iPhoto