I'm running one of these on my free EC2 account and can attest to the ridiculously easy part. It took me < 5 min to setup. If you want to avoid paying any fees, just have to make 1 change to the torrc file bandwidth settings. Also, make a great ubuntu sandbox to play with. For example, I'm running a joomla test server with it.
I also am running a Tor relay on EC2, and I was under the assumption that I wouldn't have to worry about charges with a stock install. Can you provide more detail about what I should do to my instance to prevent charges?
Edit your your /etc/tor/torrc
And change the AccountingMax line to:
AccountingMax 3000 MB
This will reduce the monthly usage to 12GB and keep you under the 15GB limit. I've been running this bridge for a few months now and have never gone over.
