There are hundreds of different fonts to choose from, but keep in mind that visitors to your auction page will only be able to view them as you intended if they too have that particular font on their computer.
For this reason, it's better to stick to a few commonly used font faces such as Helvetica, Arial, Comic Sans MS and Verdana (the default font, should you choose not to specify a particular font face, is usually Times New Roman).

Here is the HTML for changing font face-

<FONT FACE="helvetica">This is Helvetica font face</FONT>

<FONT FACE="arial">This is Arial font face</FONT>

<FONT FACE="comic sans ms">This is Comic Sans MS font face</FONT>

<FONT FACE="verdana">This is Verdana font face</FONT>