I agree with AlmondCrafts. Find. Out the cost (make sure you ask for both first class and priority - sometimes first class is cheeper, sometimes it costs the same.) and then tell your customer that you can't change a shipping price. Shipping prices are out of our control, for the most part. It costs what it costs.
It's good to make customers happy - but this is Etsy, not Walmart. Generally, you're not selling a $100 product at 85% markup...
IMO, she should be happy she's getting a great deal on the cameras, and realize that it costs to ship things. If she doesn't, than she's trying to get something for nothing. Someone else will buy the product if she doesn't. Maybe at full price.