City Lights on Eglinton Street is only 2 minutes from Eyre Square.
Hoewever, if you are willing to steer away from the city centre, there is a brilliant shop called the LightHouse which is beside Flaherty Markets (wholeale electrical) just off the Ballybrit Dual Carraigeway, near HP factory. I was very impressed wiht this place when I was there last year.
I have no connection with this shop, before you ask.
City Lights is quite expensive and stock a lot of rubbish. Haven't been to Lighthouse but Flaherty Markets also caters for the public and not just the wholesale trade and they are not bad either.