Thanks for the heads up amma! When you order those boxes online, they make you "sign" a contract that is so bizarre. It says you can't use them for anything but priority mail. I've seen some creative garage sale signs made from those boxes! LOL!
I ship a lot of stuff FedEx through my business and I've found their ground service is quite reasonable. And you don't have to pay for tracking. Plus your package is insured for $100, which is included in the price of shipping. The USPS should be worried about their competition.