I'm a postmaster in a one person office. The flat rate boxes are only a good deal if the item is heavy for it's size. Get yourself a scale and weigh item with packaging, go to usps.com and you can figure your postage and compare the different services. You can use this service even if you aren't printing the postage yourself there. You can even send for the Priority packaging, free, to be delivered to your home. Though there are some unpleasant people in the P.O., most of us try to be helpful. Various studies done by Consumer Reports have given us higher scores for speed, cost and efficiency than our competition.