With the Newtownabbey store nearing full closure (all Lego cleared within days of the closing down sale beginning - I think someone must have maxed out their credit card to make a killing on eBay) the Sprucefield store now has 10% off all Lego, which will bring it down nearly as low as Smyths prices. I think remaining stores will have the same deals, and with the prognosis being poor, the deals should get better.
It's sad to see, but Toys R Us made the massive mistake of relying on the brand name. Smyths seem to be competing rather effectively with supermarkets, Argos and even Amazon, but Toys R Us never did.