Raise your extremely reasonable prices? Look into other shippers?
Your contact frames are absolute steals. I couldn't make them for what you charge, at least not without making a large run at once. Your chemicals are cheap. I would pay 25% more for them, personally, and I do not have a ton of money.
You can't be paying for people's shipping. First things first, raise shipping prices to the point where you are not taking any hits on shipping.