Very fabulous idea!
I show a few chickens and need a fair number of leg bands, so I'm not really overloaded with them. But I have wished I had an array of colors instead of just one, because then a think a show judge is more inclined to think my same-breed same-variety chickens may be from different owners and perhaps take more time to carefully evaluate them against each other.
I have had one judge not bother to even place mine against each other when I entered them as a trio, and then when I asked specifically for him to do so, he didn't bother to really ascertain their relative quality. It seems he basically figured, "Oh, the same owner is going to win 1st, 2nd & 3rd anyway, so I don't need to take time to evaluate which chicken is truly best."
Anyway, it is important to me that when I do all that's involved in raising my chickens, preparing them for a show, plus pay for them to be judged, that they
BE JUDGED.
OK, rant over. I reckon the above really belongs in another topic category.
Back on topic: I've got green numbered bands in whatever-size-it-is that-fits large fowl Ameraucanas, and would be tickled to swap a couple with any people who have other colors.