For city centre location but very basic accomodation try Paramount Hotel , Templebar, at the Turks Head. Its been recently renovated and the rooms are clean & nicely decorated.
Stayed there last year on Friday very close to Christmas when lots of parties on, ( thats what I was doing too). Only € 67 for the room, so as there was two of us € 33.50 each. THought that was very reasonable & no taxi back required either.