where to find past exams and official sample exams?

where, where, where?

http://cfainstitute.org/cfaprog/resources/sampleandmockexams.html

Past exams? You have a better chance of going back in time and taking past exams than finding them today.

The Boston Security Analysts Society has an online test bank and a new practice exam based on the new BOK that you can buy online (www.bsas.org/pe).