I make my living as an Architect with my primary software tool costing $1200 per year in licensing fees. I will never complain about that cost as it enables greater efficiency and ultimately, higher financial returns. Anyone so dedicated to Sonar that they have been around for what could now be decades (yes, plural) has likely either made substantial money off their use of the software or found it so indispensable as to be worth many multiples of their actual investment over the years.
I think its important to stop comparing your price against another user's and deeming the difference unfair to one party or the other. Is the price you are asked to pay fair relative to the value you derive from the software? If it is, get out your wallet. If its not, you might consider moving on to another product with higher perceived value, or simply don't upgrade...but you are surely not being treated unfairly.
Indeed, everyone has an opinion, but we are certainly not all entitled to our opinions. The response to Cakewalk's announcement has been overwhelmingly irrational and disrespectful on the forums today. I believe it ought to be more thankful and congratulatory.
I am excited for the future of Sonar.