To send a package First Class with one bar of soap it would cost the buyer around $3.50 (I'd love to offer free shipping but it's just not feasible). Most people purchase more than one bar at a time, postage goes up as the weight goes up. It only takes a bar or two more to reach Priority prices.
I can get up to 8 bars of soap, possibly more depending on the size of the bars, in a flat rate envelope. There are boxes called Scotty Stuffers that are made to fit inside one of these envelopes, just had to order more. I get the flat rate price with a bit of protection for the soap.
Priority is better for timing. I work compacted work weeks, 12-hour days, 3 days on 4 days off, then 4 days on 3 days off. When I receive orders on the days I work I can print Priority labels and get the package ready when I get home. The package is picked up by the postal worker the very next day. Shipping quickly is very important to me. Priority labels are the only labels I can print at the moment.
Priority is faster by a few days.
I can get free Priority boxes and envelopes from the Post Office, they deliver them to me for free, too. Anything I can save is reflected in my soap prices.
So there you have it. I want to offer the best service possible to my customers and to get orders on their way quickly, Priority shipping is my only option at the moment.