I did .. i tried everywhere. It's my first apartment so I wanted nice stuff but at reasonable prices. I also had time while it was being completed to take a look around. So basically:
Blanchardstown has Carpetright and Tilesavers (my friend got her tiles here) but only expensive furniture shops (e.g. classic furniture).
Liffey valley doesn't have anything.
Airside retail park Swords has Carpetright aswell and B&Q which was good for Bathroom fittings (them or good old Argos). Airside also has Land of Leather where I got my couch - they always do bargains so actually yeah .. they are good value - but be prepared to wait months on delivery!
Navan has a big business park (bloomfield or something) which is all furniture places and I found it expensive.
Then Flowerhill was brilliant very reasonable for furniture. They have a variety of different qualities and like anything you get what you pay for. But all these furniture places all have the same stuff in them so I knew that they were good value. (For e.g. I saw the exact same table in Flowerhill for cheaper than i had seen it in the Navan business park 5 mins drive away). I was told to go to this place by two unrelated people and they told me in the shop that they normally get most of their customers !
Just to give you an example I got a set of furniture but I got it in cheapish wood (maylasian hardwood .. but it's my first apt

) but it's heavy and looks good - basically a dining table with matching coffee table, tv unit, and lamp table, and 6 real leather for €770 with free delivery!
There is also a furniture place in Ashbourne (Ashbourne fittings and furniture) which has pretty funky stuff at reasonable prices (but at that stage I had already got my furniture so no funky stuff for me).