I go though the same thing each year as well with mutiply rego's.
Back in June I couldn't stand the thought of having to pay $670 for one of my cars so i didn't renew it. (Car in question only gets driven about 10times a year.)
Lucky for me this car is 25 plus years old, so I did the ground work and hit the car club i'm a member with to apply for Historic Rego.
Cut a long story short, I now get to drive the car any 45 days of the year and it only costs me $64 a year
, plus insurance is cheaper as well.
Cheers Mark.