I just started my Hitchcock collection. All I can say is WOW, what a head ache trying to find out what has what and where to start. I bit the bullet with the Universal Collection vol 1 and 2 just so I could get the AH Presents vol 1 and 4. I will have four dupes.
I purchased at DDD and Amazon Marketplace.

Universal release
Alfred Hitchcock Collection vol. 1 comes with (AH Presents vol 1)
Alfred Hitchcock Collection vol. 2 comes with (AH Presents vol 4)
Best of Hitchcock vol 1 comes with (AH Presents vol 2)
Best of Hitchcock vol 2 comes with (AH Presents vol 3)

Warner Brothers release
Alfred Hitchcock Signature Collection

The link below helped me tremendously as well as all the threads and topics in this awesome forum.

http://www.daveyp.com/hitchcock/index.php
....Look for box sets, collections and other releases.