Not sure if this will help you but I have a few items that are billed in USD and since QBO gives only the option of entering the price in CAD for a saved product/service I've added "USD $150.00" to the product/service description.  When I create an invoice using that item I have the USD price - I still have to enter the USD price into the invoice but it saves me from looking up the price when I'm doing a lot of different priced USD items on one invoice.  It's a workaround for now but I too would like the option of having CAD and USD pricing on a product/service item.