I experienced something similar a year or so ago. I was buying the new modem that had come out, and wanted to get other items. So, I was coordinating with support. When I asked about the high cost of the shipping the person I was working with said they would check with their team to see what the actual cost of the shipping would be. It went from $40+ dollars down to $4 or $5 dollars.
It seems like there is some sort of glitch or error in their ordering system that is doing the calculations wrong?
I would just contact support when you are ready to order and ask if what the system is showing is the actual shipping costs. They might be able to help you.