I stayed in a hotel called Blooms
www.blooms.ie
It was €89 per night which is £65, so not too bad. It was basic no frills but everything that you need bed, shower and bar! Breakfast was included and was a reasonable buffet with your standard fried selection plus fruit, croissants etc. The hotel also has a night club attached "Club M" which hotel guests get free entry to on a Friday night. Only downside is that the road outside gets noisy early in the morning (7am) and so you may get disturbed by this.
It is in the Temple Bar area which is the popular area for night life with plenty of choice for food and drink. It was 5-10 mins walk from a large shopping area. At the bottom of the street with the hotel on was a bar recommended by the taxi driver which has a good restaurant upstairs "oliver saint john o'gogarty's" or similar spelling. They have live Irish music there every night. A little further away was a large bar and night club "Fitzsimon's" which had live music from different acts every night. Everything kept going late, I was working each day afterwards but found it difficult (even impossible) to go back to the hotel before 2am because the atmosphere was great.
Took 30-40 minutes by taxi from airport and cost €25-30.