Go to the buy page, and is written in the low right hand corner :
Special Cases
If you wish to upgrade a discounted license to full license for the difference in price, inquire about bulk license discounts, or have any other special licensing needs, please email licensing@cockos.com.
So basically you will have to pay $10, just ask them.
Wow that is good to hear. Thanks for this info!
Edit- Got an email back from them, there is no discount for previous owners, you have to pay the $60.....
Oh well still cheaper than Cubase and ProTools