Have found Julius Marlows to be quite good. Definitely get the longevity out of them. Windsor Smiths are up there for longevity as well.
How the heck did you get to 4M posts?!
Sounds about right
Interested to see what CB Radios you're looking at mate. We've got cheap ones from Repco. $30 for 2. Mike and I keep them in our cars and lend them as required.