How long do brakes usually last?

[ds06nomad]

I know it varies from rider to rider as everyone brakes differently, but ballpark: how long do brakes last? I use my rear brake primarily and only engage the front brake when necessary. I'm getting a new rear tire next week and was wondering if it may also be time for new brake pads (at least in the rear while the wheel's off).

Also, how much do they cost and what 's a good brand of brake pad?

Thanks a bunch,
Daryl