It should have six DVD/Blu-ray. There are also six of them in Amazon page. I think the episodes may be distributed like this.
Hitagi x 2, Mayoi x 3, Suruga x 3, Nadeko x 2, Tsubasa x 3 and Tsubasa x 2.
Edit: Wow!
When I write this, all six Blu-ray are in the top ten of Amazon page. Very impressive.