Thanks everyone, the knowledge & information posted here were very helpful.
I passed all my CPL exams, one each week, mostly in the gaps of driving cabs only because of the bob tait books and info here. Bob tait books are best in the market for sure.
IREX now, I might be wrong here, during my search on Bob tait web, irex online exam prep says RPL exam material,
"IREX Price: $77
In order to get an idea of what awaits you in the CASA Cyberexams, this RPL Exam Prep includes four on-line exams of a very similar standard to that expected by the CASA examiners. "
i might be wrong or just a mistake.