Mavericks can run both Office 2008 and Office 2011.
Office 2008 is end of life software and will receive no further updates. Surprisengly, Microsoft Office 2008 for Mac Special Media Edition Upgrade is only $39.90 on Amazon. Other version that have the same thing but without the Expressions Media are over $100. You would most likely need your Office 2004 CD to prove you own Office when installing since it's an upgrade installer.
Office 2011 is due to be replaced later this year. Microsoft seems to be going to subscription service only for Office nowdays. The best deal I've seen for Office 2011 is on Amazon Office 365 Home Premium 1yr Subscription
Regular List Price: $99.99 Price: $67.15
Licensed for one user to install on up to five devices.
The benefit of buying Office 365 is you automaticaly get upgraded when the new version is released.
If you do buy the boxed version of Office 2011 and need email, the Home version does not come with Outlook. You have to purchase the Business version to get Outlook.
Office 2011 includes activation now. If you purchase a boxed version you need to buy for the number of installs you need. In the past we could install on one computer and one laptop. This requires a two install license.
Hope this helps!