Mike,
I packed them the same way I always do - in a #10 envelope with the chips wrapped in bubble wrap and taped up on the outside of the envelope with clear 2" wide packing tape.
I still think you get a different rate depending on the clerk - they all figure things in a different way, envelope vs. package, plus weight and thickness, etc. - I get a different price almost everytime I ship something and I have given up arguing with them.
Take care,
Jerry