This may not be for everyone but if you work for a large company who has microsoft products on the desktop, you might find your company is part of the microsoft home use program.

This program offers massive discounts to employees for products that the company owns. You can get office 2007 enterprise for $19.95, you need a program code and a company email address.

Just ask your company if they participate in hup program...

https://hup.microsoft.com/

the home use program is only available to employees of microsoft® volume licensing software assurance customers. Only employees who received eligibility notification directly from their employers are authorized to use this site.