Congressional candidate JoAnna Mendoza can quickly rattle off prices from the grocery store in the small town of Eloy, Arizona, where she grew up. A couple of months ago, a pound of ground beef was going for about $13, a tomato was $1.50 and “a freaking cucumber was like $3.” She knows because she’s a single mom to a 10-year-old, and she’s struggled with the same things most working women are facing: finding a steady job, a good pediatrician and…