Thanks to reader @stephy_ygl on Instagram for this tip! Right now on the Sephora site, you can get the Demon Lover Duo Eyeshadow for $15 (regularly $35). Only this duo is on sale, and I believe this deal is online-only (if you're able to get this for $15 in-store, I would love to hear from you!). I wouldn't wait too long if you're interested though--sometimes these secret sales sell out pretty quickly.
Thanks again, @stephy_ygl, for the tip about this one!