All I know is I paid $59 for 10.5 and $99 for 11.
Others in this thread have said a .5 release can be had for as low as $40. I'm too new to Cubase to have personally seen that. I started with buying 9.5 on sale and not registering it until 10 came out. Then I sooopidly bought and registered 10.5, which resulted in me buying 11 (since I wanted it).
From here on out, I'll only buy the .5 releases and save them for registering after the next full version is released.
Thanks to cclarry (aka Larry Shelby) for enlightening me.