How much does it cost to implement Security Engineering practices?
I depends... :-)
But here is one example of not implementing it
163,000 customers were affected by security breach and the company pays $10, 000, 000 fine
http://www2.csoonline.com/blog_view.html?CID=27297
Still hesitating to implement it or not?!?!?!
Stop hesitating and get started with http://msdn.com/SecurityEngineering