Give some stickers away, they are very inexpensive, especially when you order in bigger quantities. They only get cheaper per piece as the quantity goes up. At the end of the day, you write it off as a marketing expense for your business. Think about it. . .
You order something online from your favorite online shop, stickers are something you least expect and they add 2-3 stickers, what's your reaction? "Awesome!" "Dope" "Hell yeah!". And what do you do next?
You are most likely to stick them onto your laptop, vehicle, skateboard, books etc. You're given a "WOW" factor by just a simple free sticker(s).
We did say you can sell them. You can sell them in sticker packs, which usually have a combination of 2-4 different designs and 2 stickers of each design. It doesn't have to be like that but you get the point. To build the value of the sticker pack, make those stickers limited and exclusive. The same thing though, they are inexpensive to create and help build some income and brand awareness.
In conclusion, whether you agree that stickers should be free or sold, stickers are a must have for any kind of brand. They help you spread awareness, easy to market to the masses in your community and a great way to express your creativity.