Currency format depending on drop-down box
 

I'm trying to make a pricing spreadsheet for our offices around the world. I
want each users to select a currency from a drop down and for this to update
all the currency cells to their chosen symbol. I can't rely on the local
currency (as set in Control Panel) since each office may quote in different
curencies (eg New Zealand office may quote in NZ$ or AUS$). How do I write a
format so that it will pick up a cell reference rather than littoral
characters?