I ordered from eggcartons.com and am a very satified customer. Plus they are a BYC sponsor.
I don't know that they are the absolute lowest price, but they definately are competitive with where I looked around, their shipping costs were reasonable and the service fast and great.
I ordered from them because they carry the paper cartons that easily split to form two cartons of 6. I like those because I give away my eggs and often someone will just want 1/2 a doz so it makes splitting the cartons easy.
The best deal is www.eggboxes.com. I just ordered some last wednesday, i think.
They have free shipping.
I ordered 150 misprint cartons for $34.50 w/ free shipping.
or you could get 150 non printed cartons for $40.50 with free shipping.
I hate to pay shipping. So this way, you get cartons that are a very cheap price, the cheapest price that I have found on the internet, with free shipping.
They have paper, plastic, styrafoam, and egg cartons that split in half.