Can anyone help me out?

I have often parked close to the airport and seen people using scanners and
it has peaked my curiosity.

I know nothing about the subject of scanning but would like to learn.

My questions a Where can I buy a scanner?
How much will it cost?
What can I listen to?
Do I need lessons or training?
I heard that the police use Digital, can I
buy a digital scanner in canada?
Is scanning a worthwile hobby?

Any comments appreciated

Thanks
Steve