I've commented before that, even as a kid, I never liked the Domar-based economy of Gamma World. It seemed silly to me that an Ancient, hard-plastic currency would still be in use, when the post-apocalyptic residents should be melting it down for armor and weapons.
In my current campaign, I've played a bit loose with the economics, and the barter system reigns supreme. The closest analogs to "hard currency" I use are scratched-up Ancient CDs / DVDs and credit cards, with values fluctuating based on color, logo, text, holographic embossing, etc....
...but after seeing these pics of the "Colour Chiefs", I may have to revise my system. I want ALL my Mutant Future future mutants to dress like this.
(Images first seen at How To Be A Retronaut, but originally designed by The Library.)