[vladvasiliu]

> Also, don’t assign a EIP to your EC2 NAT instances (unless you absolutely must persist a given public IP) as that counterintuitively routes through public traffic. Just use a auto-assigned public IP (no EIP).

Could you point me to somewhere I can read more about this? I didn't know there was an extra charge for using an EIP (other than for the EIP itself).

[m1keil]

I'm highly skeptical of this claim as well. Going through NATGW with EIP or auto-assigned IP is the exact same cost for the actual traffic.