Macker2,
Haven't come across any cheap sites and think I asked the same ? a while ago and did not get any positive replies - anyone?
You can get the free discount/loyalty cards with Smyths (who are usually the cheapest) or GAME. The conversion from stg. is what appears to make GAME's ones so dear. Electronic Boutique were the same before GAME took them over.
There's a shop in Liffey St. that does 2nd hand games and I think its called Gamesworld. There used to be another in Talbot St. but cannot remember the name. Its a long time since I was there but I think its near a bridge, not far from Guineys but on the opposite side.