Cambria batteries could be a good barter item if they are rechargeable. We have a solar battery charger and batteries and had not thought of those as a barter item.
I just read an article on a bag to protect items from an EMP pulse. One item they said to but in it was a cell phone and laptop. Hubby laughed saying we would be the only people able to watch videos on our laptop and see photos on our phones. If the EMP is large enough he said it would take out all need for these items. I reminded him we have mother Earth News on cd we could access with a laptop.