While I wait for my sample orders to arrive. I am going to get a patchwork system running on my RasPi.  I need to get rotating mac addresses, as well as some sort of smart traffic monitor that will only start an exit node if there is a certain threshold of traffic already passing by.  This requires promiscuous mode to be enabled, and I don't know how much that is going to effect power requirements.   

Also, I need to start looking at passive ways of collecting power that are super cheap. My hope was to be able to run a node with a watch battery, but I see now that this is infeasible, especially to be a useful exit node.  The power requirements are going to be much higher.  The more battery though, the higher the cost.   Arrrggghhh. 

Here is a good article I found comparing power requirements for different wireless standards.  

http://www.digikey.com/en/articles/techzone/2011/aug/comparing-low-power-wireless-technologies

It's a bit dated, but It really put things into perspective.