Budget hotels in central Dublin?

Take a look at the Belvedere Hotel; near the Garden of Remembrance, center City but away from the Temple district, which can be noisy. We stayed there in September 2016, it was clean, quiet and has a breakfast buffet. It is not new and shiny; clean and comfortable beds, decent bathroom, which is all we were looking for. It offers an Irish music night that is aimed at tourists, but does have good music. We were the only Americans there that night; mostly Brits, some Dutch, and a sprinkling of other nations. We took a bus in from the airport on the Dublin Pass. We stayed at the Holiday Inn Express near the airport when we flew home; it was fine and the shuttle was on time--did have to walk to the hotel next door to catch it, but that one was substantially more expensive.

Dublin is a very expensive hotel city. I suggest going to Booking,com and filtering your search from low to high prices. Then look for customer ratings that are substantially higher than other properties in the same price rsnge. I go Trip Advisor and read what customers have to say about the properties before booking them.
I have never been dissatisfied in booking relatively low priced rooms this way.

I have stayed at a lovely hotel, Buswells in Dublin and enjoyed my stay there. I stayed before and after my RS 14 day Ireland tour. It is in walking distance of a lot of sites and Trinty College.

Anchor Guesthouse on lower gardiner st... I have stayed there 2x and I will stay there again the end of the month. Rooms are clean and basic, breakfast is great, location is wonderful.. O'Shea's on the corner is a great pub with great food...

Have stayed in both the Waterloo ( mentioned in Rick Steves guide) and the Skylon. Both under 150 euros, both convenient and both totally acceptable.