I understand that Snap On dealers offer a test for Snap On torque wrenches.
As for the cheap end , The worst one I have seen , Not sure if it even available now was a metal bar with another bar and handle with a scale at the top , You had to pull as hard as you can and bend the bar then try and see what the scale said
I found one, click on the image ,
I would imagine that would be like playing darts with a blindfold on . very accurate.