There is a company in Annacotty, Limerick (Shortts Stainless) that sell Stainless steel in sheets 1200 x 2400 or 600 x2400 in various thicknesses.
Details from goldenpages.ie are:
Annacotty Bus Pk, Limerick
(061) 216000
I don't know if they ship to Dublin but they are quite a large compnay so i imagine they are Nationwide
Regards
Jon