Maybe they've been there for a while, but I don't remember seeing them. Individually for $24.99 in HD  or $4.99 to rent, or available as a bundle of the three movies for $44.99.

You can also buy all three books in digital form for only $17.99.

I've read the series three times, watched it twice, but still tempted to pick up digital copies. Once our kids destroy the DVDs we have, I'll come back for the videos.

Lord of the Rings in iTunes