The total TCGPlayer mean cost as of July 21, 2015 is:
1 $489.37 Burning Abyss
2 $470.93 Nekroz
3 $293.84 Ritual Beast
4 $455.34 Qliphort
5 $574.73 Shaddoll
6 $282.82 Yosenju
7 $392.73 Tellarknight
8 $325.93 Yang Zing
I am excluding Number 106: Giant Hand in the Yosenju list in the price calculation. I plan to replace this card with the cheapest card I come across.
Deck 1: Burning Abyss
Deck 2: Nekroz
Deck 3: Ritual Beast
Deck 4: Qliphort
Deck 5: Shaddoll
Deck 6: Yosenju
Deck 7: Tellarknight
Deck 8: Yang Zing
In later posts I plan to track my progress in assembling this cube. My current estimate is that it will take me three years from today to complete, and that is because I aim to wait for as many reprints as possible before buying what are now very expensive cards. At this early stage, I plan to pull from packs as much as possible. Yes, I know, singles are a better idea, but where is the fun of that!
Here are the multi-use cards. The maximum number is the one needed to build any one deck.