the wizard of oz is a miss, the only reason the shoes were red was for panavision to show off their new lens technology and how the color remained consistent at all focal lengths. in Frank L Baums original book the wizard of oz the slippers were silver, it's an allegory about getting the US back on a silver standard. watch the secret of oz for more info.
watch the film it is well documented. I'm no stranger to symbolism and child ritual sacrifice. keeping research factual is key. frank l baum was againt the gold standard because the majority of the gold was owned by the robber baron and they could manipulate the market.