$100 annual subscription. There's no option to buy them outright with a one-time payment.
If you have a Mac, consider Apple's iWork package, which comprises of Pages for word processing, Numbers for spreadsheets and Keynote for presentations. Each app is $20, so you pay $60 for the package. Comparable apps are available for iPads and iPhones — for $10 each, or $30 for the set.
The Apple package is cheaper than Microsoft's. It's not as rich on features as Office, but it has all the things most people need. It's also better at automatically saving interim revisions, in case you need to go back to an earlier draft.
The problem comes with sharing files. It's likely that the recipient of your file won't have Pages or Numbers to read it. Apple currently doesn't make the software for Windows or Android devices. You can export files to Microsoft and other formats, but that's an extra step to take, and you risk losing some of the formatting. Pages and Numbers are good primarily for Apple users who create documents only for themselves.
That said, Apple is releasing an online version of iWork this fall, opening it to Windows and Android users as long as they have continuous online connections. Apple hasn't announced details on pricing.
Google Docs is a package that works on any computer with a Web browser — Windows, iPhones, iPads, Android and, of course, Google's own operating system for laptops, Chrome OS.
It's free, and there's no software to install — everything runs on Google's servers over the Internet. Like iWork, interim revisions are automatically kept in case you need an old draft.
But Google Docs is short on features. It lacks the option to automatically hyphenate words at the end of a line, for instance. Spreadsheets are limited to 400,000 cells, compared with 17 billion for Office. Google Docs also needs a constant Internet connection to run smoothly. An offline app you can enable for Google's Chrome browser is more of a stopgap. There's no spellchecking until you are back online, for instance. (That said, the online version of iWork doesn't work offline at all, at least in its beta test form.)
Both iWork and Google Docs have good auto-save features. If your power goes out, you won't lose an entire day's work. Office has a mechanism for recovering files following crashes and power outages, but it's not as reassuring as a real save.
Winner: Office for