Amazon has free Christmas music downloads, but I do feel obligated to warn you that they are not all really Christmas music. The Boxmasters' single seems anti-Christmas and actually has an "Explicit" warning on it!
That said, it's still free downloads, and their handy-dandy MP3 download tool makes it easier to do (and loads it straight into iTunes for you).
Don't worry (as I did) that you missed a few days...Amazon allows you to download all the songs so far this month!
There is a really pretty "Coventry Carol" available that I would highly recommend as a remedy to the noise and bustle that seems to be everywhere. Just look for the album cover you see to the left.