but you said you are going to be taking a bunch of readings, and then average them, correct? so what is the problem...
accuracy in equipment is nothing more than a factor of tolerance ( and price, for that matter), and tolerance is a mathematical entity that can be reduced by the number of instances being averaged, with the addition of time spent, of coarse.
I guess the real quest will be to find the sweetspot, where money spent on testing equipment, will complement the time spent on doing so, without rendering the tester financially deceits.