The valuta value for pricing is standard set to Euro, because I live in The Netherlands and Euros are the standard for Europe.

If you need to change the value to lets say AU or $ you have to change the following lines in the language file.

var $PRODUBK_0010 = 'Euro';
var $PRODUBK_0077 = 'euro';

Set these parameters to the value you require.

For example

var $PRODUBK_0010 = 'AU';
var $PRODUBK_0077 = 'AU'; 

The language file english.php is located in the subdirectory 'language' of the com_productbook directory.

P.s. I found the JoomlaXplorer extension of great value to do these kinds of things online!