Anyone who's tried to order more than one thing from RA lately has seen the strangeness their shipping algorithms now employ while figuring up the total bill. I may have stumbled upon a way to defeat the insanity that can sometimes ensue when ordering several parts that show to be shipping from more than one location (and thus tacking on extra shipping charges).
This is hard to describe via text, and I only really stumbled upon it while trying different approaches, so bear with me:
1. For a part that shows to be shipping from a different location than other parts in cart, go back and add several more of that same part to the shopping cart.
2. View cart and see if any of the newly added parts ship from same location as original parts. If so, remove all newly added parts from cart.
3. The cart should now hold all the original parts and no extras, and if this trick worked like it did for me, all the parts will be shipping from the same location.
NOTE: if you start out with more than 2 different shipping locations, this may not work in its current form. I think the shipping logic can still be circumvented by using a form of this work-around in that scenario, but it may require more iterations of the second step to get all items into one shipping warehouse in the cart.
Hopefully that's a little more clear than your average mud.
Good luck,
Nuke