Is there any chance that a flash drive is available to purchase the upgrade to MasOS X (10.9.2). To download the upgrade for 4 computers is far more than I can download through my internet service provider plan.
Not that I'm aware of.
Just download it once.
After the first download, stop the installer and copy the Installer to a USB stick or external hard drive. Copy it to all of the other computer's Applications folder and run it there.