In his popular plaintiff-oriented book David Ball on Damages, David Ball has a section titled "The Best and the Cheapest," which begins like this--
Who are these mystery experts? Look for them among "the best repository of testifying experts you can find: high school teachers."
According to Ball, high-school teachers are both cooperative and skilled at explaining difficult concepts to a lay audience. They also have built-in credibility in the community. As Ball writes, "They need not provide opinions. All they have to do is explain (and perhaps demonstrate) a principle or a process." (For more on this point, see my last post about experts.)
Finding an expert from among local high-school teachers is something I've never tried myself, but it's a tip worth thinking about.