In true OzB style, I played around with the link from Catut's post and managed to bring the 15% discount up to a whopping 50% off, just by changing the numbers in the Url!
I couldn't bite the bullet with 15% off, but at half price, I was sold.
Works for all subscriptions!
Enjoy!
Also selecting Physician assistant student drops the cost. Not sure if that has an impact on any of the content though.