Can anyone tell me which Argento documentaries are available on DVD (either alone or as a supplement to the film)? I know that WORLD OF HORROR was on DVD from Synapse as well as on the Dutch STENDHAL DVD. I know EYE FOR HORROR is available as well.

But I understand there are two other Italian documentaries. MASTER OF HORROR was reviewed in VW 16 and had behind the scenes footage from OPERA and THE CHURCH and the other more recent Luigi Cozzi was included on the Japanese PHENOMENA laserdisc. Does anyone know if these two are available on DVD? I'd like to see the behind the scenes footage on THE CHURCH.

Yeah, there's Dario Argento: Master of Horror (by Luigi Cozzi, 1991), and: Mondo di Dario Argento 3: Il museo degli orrori di Dario Argento, Il (also by Luigi Cozzi, 1997). I've only seen the first of those, and it was pretty good.
As far as I know, though, neither are available on DVD. The '97 one was going to be featured as an extra on Dragon DVD's Unsane disc, but I don't believe that ever came out.