I have stayed before nearer to the Mezquita but it was easy to book on the internet for the Hotel Boston in the Plaza de las Tendillas in the heart of Cordoba's main shopping area. It is not far from the train and bus stations though bus 2 will take you if you are heavily laden and it is only about 10 minutes to the Mesquita. The hotel has en-suite rooms with good showers, very large towels and very comfortable beds. Reception is helpful with quite adequate English. Coffee and beer are available at any time and breakfast costs €3.50 [Feb 2004]
Having felt hard done by booking an expensive hotel in Seville, I was delighted to balance the experience with an inexpensive hotel in Cordoba. Centrally located, the hotel is a fair hike from the train station but easy to find. There is a grocery store about a block along the street with the hotel. There were no frills but the room was clean. The bathroom was small but everything worked. This was an interior room, so there was no view but the room was quiet. Not a room where you want to spend a lot of time, but ideal for dropping your bags and going exploring. The best price I found for April 2008 was on Venere at E42.