NIS 2012 Subscription Renewal Pricing

My current subscription is soon due for renewal. I can do this online for AU$79.99 or upgrade to Norton 360 v6.0 for AU$99.99

 

However, I can purchase Norton 360 from a local retailer for AU$108 and get AU$60 cash back if purchased before 30April, effectively only costing me AU$48 for the upgrade, ie less than half price.

 

Why should I purchase online, Mr Symantec? Am I missing something here?

 

There seems to be a significant disparity between costs to current (preferred?) customers and potential 'new' customers. Also, these cash back offers happen often.

 

Can someone please explain?