If you are thinking of buying Office 2007 for a computer that didn't have it before, you may think you are stuck buying it at full price. You are not.

You can save some money by buying for example "Microsoft Works 9.0" and then the "Microsoft Office 2007 Upgrade" which is combined often much cheaper than the same suite without upgrade.

You may also qualify for the upgrade price with older Microsoft software you already own. Office 2007 can be upgraded from "Microsoft Works 6.0-10; Microsoft Works Suite 2000-2006 or Later; Any 2000-2007 Microsoft Office Program or Suite and Any Microsoft Office XP Suite." according to the information on the Microsoft website.

Just make sure to compare the Office suite versions so you buy the one with the programs you want. http://office.microsoft.com/en-us/suites/FX101635841033.aspx
Oh - and the same way you can save on many single components like Word 2007 if you don't need the full suite.