Costs (in Euro) per day for two people sharing: cheap but not rock-bottom. We used public transport, stayed in cheap hotels, ate local vegetarian food, drank a lot of gourmet coffee, hired a scout and a mule driver in the Simien mountains, and visited all the tourist sites. Total per day was about 26 €, not including the flight.
Further information on our Ethiopia travels:
http://westwards.typepad.com/westwards/ethiopia
http://westwards.typepad.com/photos/ethiopia_201012
