Hi Brent and welcome to the forum,
That is a problem with using multiple suppliers, but the suppliers are the ones that set their shipping prices. I wouldn't be suggesting listing a bundel package from more than one supplier, that has all sorts of potential to get messy. It's not just a crazy shipping price you will end up with, but quite possibly different delivery times to the customer as well.
If you're going to bundle, you want everything arriving to the customer at the same time.
The best way to keep the shipping costs down is to nego with your suppliers, see if you can get shipping discounts based on multiple orders.