HT4854: How to install OS X on multiple computersLearn about How to install OS X on multiple computers
Currently Being ModeratedDec 5, 2012 6:17 PM (in response to brent7777)
Do you have an Apple store within a reasonable distance? I'd consider making an appointment with the Genius Bar and purchase it there (bring your machine) and have them download it for you. When the download is finished, dismiss the installer and copy it (it's in the applications folder) to another location (folder or external drive) - then you can install (the installer self destructs afterwards). This way, you'll have a copy of it if you need to reinstall for any reason.
Currently Being ModeratedDec 5, 2012 6:48 PM (in response to brent7777)
You do need to bring your machine because the purchase will be tied to your Apple ID and the machine ID. Just explain that you have very limited internet access and are unable to do it at home. Unless you want to, you don't have to install it while there - when the download is finished, quit the installer, find it in the Applications folder and copy it elsewhere for safekeeping. Then go home and launch the installer in the applications folder by doubleclicking it.
Make sure you have a backup of everything just in case.