I am trying to find a way to offer a one cost option or a low-cost option. For overnight packages in a 1x1x1 box for $30, or priority for $9.00 something like this. How can I achieve this shipping rate? Do they (Major shipping companies) pre-sell labels for certain sized boxes?
      Answer1:USPS has flat rate priority mail in two sizes. Fedex and UPS are always based on zip code and weight. You can offer one-cost with UPS/Fedex by charging an avereage price and absorbing any excess or shortage.