OnePower readers are just generic progressive lens. In their ads they seem to be using single power lens. These progressive lenses have narrower fields of focus depending if your eyes are looking through the top of the lense (weaker power +0.5D) or bottom (stronger power +2.5D)
Costco, BJ's, Walmatt, Amazon, 10-packs of readers for Cheeeeap, single-power. Wal-Mart has a spot where you can find your ideal strength for free, unmolested by salespeople, why would you do anything else?