I guess it does depend a little bit on the grocery store. I'm more accustomed to seeing store brand price range comparable to Aldi, aka $1.50 for the bottom range for the varieties that have added sugar, and $2 and up for the "authentic" or organic varieties that don't have it.

As for Prego, well I'm probably actually thinking of Ragu at the moment but they have "Simply" or "Kettle" or "Homemade" or authentic or organic styles that don't have added sugar. Not sure remembering all the right names for them, but having sauce without added sugars something that people seek out a lot easier so it makes sense that brands try to varieties to accommodate that market niche.