Before purchasing additional fonts for MS Office it is worth checking if someone will be able to view it on another computer.
Some clients choose to buy non-standard fonts. To ensure that your documents display and print correctly you need to check that the font is available on any computer that they will be viewed on.
If you choose to use a non-standard font and you cannot control where the document is viewed then the obvious work around is make a pdf. The benefit of this route is that the person viewing the pdf cannot edit it.
If you want to greater control over how your document is viewed in Microsoft Office then you need to choose from the fonts that you know will be available.
The standard fonts that are on the computer depend on the version of Microsoft Office installed.
Fonts in Microsoft Office 2013
Fonts in Microsoft Office 2010
Fonts in Microsoft Office 2007
Fonts in Microsoft Office 2003