I took one of John Powell's courses a couple years ago, he is the one that wrote all the different exams for the Oregon Supervisors tests.
He mentioned he was getting out of it for a while to go back into inspecting, you could try giving him a call to see if he plans on doing any classes in the future. You will not find a better exam prep course than taking it from the guy who wrote the test, I can tell you that!
His business is called John Powell Electrical Training and Consulting if you want to look up the phone number.
Exam Specifics:
Open-book examination, two sections. Section one contains 52 questions, section two contains 12 questions. (four hour time limit.)
The catch is you must pass each section with a 75% score or better.
On the 12 question section they give you a multi-faceted load calculation for a building(s) that includes from high voltage transformers all the way down to branch circuit receptacle loads and everything in between. If you
miscalculated something along the way it effects something else. One wrong answer leads to another. On the test that I took, 8 of the 12 questions where based on this massive load calculation. This one eats up the clock.
It is by far the toughest test I have ever taken. Get a hold of John Powell and take his course. You will be glad you did.