As you can imagine it's incredibly hard to find a place that even weaves the Colorado state tartan, much less one that would make a kilt out of it. But just from a Google search I found this on a fabric site called Spoonflower.
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They don't have it in wool, but the performance piqué would be perfect for a custom Sport Kilt! I've become a fan of those anyway. Plus there's another version in "modern" colors if you prefer that style.