I would highly recommend Terenure Office Supplies who have matched and indeed beaten Vikings prices in the past for me. Call Eoin on 01 4905772
Seperately and a little bit biased here as I helped these guys set this up but [broken link removed] have just launched, and have great prices on Business Cards, Letterheads, Stationery etc., especially as all businesses are more cost conscious than they may have been in the past.