In addition to the three volume Gray/Palmiotti bind, I'm now also planning two more earlier volumes to complete the post-CRISIS Hex:

#1: Post Crisis '80's Hex (19 issues)

Hex #1-18
Secret Origins #21

#2 Post Crisis '90's Hex (13 issues and counting):

Jonah Hex: Two Gun Mojo #1-5
Jonah Hex: Riders of the Worm and Such #1-5
Jonah Hex: Shadows West #1-3

The last one needs some padding, so I might include Vertigo's Weird Western Tales #1-4 since it's thematically related and contains at least one Lansdale story.  Maybe Generation Hex #1 as well.