No matter how well you've got your music set up, if it's too dark to read, it's going to be hard to feel relaxed about playing.
My mom RAVES about this Cocoweb light! She is a pianist who rotates playing among four churches and works with many different lighting conditions.
The LED lights should last a looong time. My mom uses the plug-in light which gives her the freedom to NOT worry about batteries. However, it does mean that the piano needs to be near an outlet.
Mother scoots her ChoreoKeeper back and forth as needed to bring outer pages within viewing range AND for good lighting.
Her 19" wide light illuminates several pages; there's also a 22" wide version (some reviews indicate that it will brighten 5-6 pages). The lights come in various finishes too.
This light is an investment, but you'll be set once you own one!