It’s generally more expensive to depart on a Wednesday, if you have to leave on this day you can still search on Cheapflights to find great options that meet your needs.
Regardless of the time of day you decide to fly, the ticket price will remain around the same. Book flights from Sacramento to Pierre as you normally would.
Great question - SMF to PIR just means Sacramento Intl Airport to Pierre Airport. Now you’ll know what these unique codes when you look for flights!