Half of the test is.
http://www.api.org/certifications/icp/Code West has the premier test prep
Mark Smith has the best training if you want more out of the class than just how to pass it.
http://www.msts-training.com/There are other places for training. Do a Google search on API Test Training
Now be advised, you need to have experience in tanks (653) Pressure Vessels (510) and/or Pressure Piping (570) to qualify to take the test.
If you have the discipline and ability to study code books you can pass the test without a prep class.
Cost to do this is in the $25-3000 range.
If you take the prep class you are looking a $5-6K Books, class, travel lodging and food.
Not counting lost $$ if your employer is not picking up the tab.