Amazon is currently running a promotion where you can get $5 off any $15+ order of Sharpie, Expo, and more office supply brands. There are over 200 qualifying items, so you should be able to find a pretty good deal on products like Mr. Sketch crayons, Paper Mate InkJoy pens, Expo markers, and more.
Please note these do have to be shipped and sold by Amazon to qualify. Add at least $15 worth to your cart and when you check-out, you should see the $5 discount applied.