There have been skin-tone art supplies available more-or-less widely for the last decade or so, and quite rarely before then, but most were in sets of 6-12. Now Crayola is releasing a set of 24 skin tone crayons plus a few extras for hair and eyes. They have a fantastic range of pinks and browns, some so-so golden tones, but not really a good olive or terracotta. It's still a huge leap forward.
Some other examples of multicultural art supplies and toys: