I thought i would share this info with my friends on the board since we all ship to each other a lot and we need to save some money.
Yesterday i got very interesting info from a lady working with the post office and she got me sample of boxes used for shipping priority but without the flat rate. The boxes are called regional priority boxes A & B and each comes in two sizes one is a top load and the other is side load. They are wonderful and a lot of time a lot cheaper than the flat rate. I tried to take a pic of the rates but it didn't come out clear but you can find all the info on the usps website and the boxes are free but you have to order online and print the labels online "which is easy to do". I took some pics of the boxes. Oh and they have this huge long box which is the same rate as the large priority box but takes a lot more stuff than the regular large box. All those regional boxes go by the zone that's why they are cheaper.
I hope i clarified some of the options and pls ask if you have questions after visiting the website and i will be happy to email the lady to clarify things for you.