Shreddi
Should I go to pro tools to avoid the constant upgrade charges?
HAHAHAHAHAHAHAH*wheeze*AHAHAHAHAHAA!!!!1
Serious answer: Absolutely not. Check out Reaper. Pay very little and get updates for like a million years. It's a solid DAW. However you certainly won't get all the extra goodies you do with Sonar though but if you are considering going to hardware anyway then that likely doesn't matter to you. I still prefer Sonar.
BTW... there really isn't ANY DAW out there aside from Reaper that isn't going to regularly charge for upgrades.
You do of course have another option and that is... just don't upgrade. It's not like old versions stop working... unless of course you upgrade your OS and for whatever reason the old DAW can't handle it but again... you don't have to upgrade your OS.