The new USPS Regional Rate boxes are fantastic. The size B box is comparable to the medium flat rate box and can, depending on where you're shipping to, be a lot cheaper. I use those boxes A LOT. And if you're only shipping 6 or 8 bantam eggs, you can actually fit the size A box inside the B box for extra protection. The cost is based on the destination zip code. The B box has a 20lb max weight I believe.