Sky + subscription is free when you take any programme package, otherwise it's €15 a month.
Sky are sending promo packs to all customers who haven't already "introduced a friend". There seems to be a variety of offers, but the most common is a free Sky+ box for the new & existing customers, but you have to pay €45 for installation.
If no-one here offers is looking for a promo code, you'll almost certainly get a taker on the satellite tv section of boards.ie.