Mmm... tricky question, as I usually don't like to have the currency changing depending on IP. Therefore, I don't if my idea is correct and surely should need to be tested.
As you probably know, the Schema.org/Offer preview the mark up for currencies.
What I'd probably do should be calling the product description, photo, prices and currencies with a PHP call (if your site is on php), and the code snippet called would be mark-up with the Schema.org corresponding to the "country".