On the main Celebrity Board on Cruise Critic a comment was made that Celebrity are offering a 1 for 1 exchange for purchase of On Board credit. With the $A tanking like it is I had to follow it up.
I spoke with Celebrity Admin and they confirmed the offer. Don't know how long it will last but is very worthwhile. $300 OBC paid in $A costs me current around $NZ320. If paid using $NZ it would cost me on exchange rate offered $380.