We don't sell our eggs we only give eggs to family and friends. So in my case, they collect cartons for me. If you are selling your eggs, you can try Amazon, TSC, or maybe a local dealer.
Welcome. I do not sell eggs. The neighbors I give eggs to give me cartons. When I take them to my family, I usually use a basket (there is one special basket I have @janiedoe), and then they empty the basket - tell me how awesome my basket is...and I take it home.