Hannons in Castleisland, don't be put off by their window display and frumpy exterior. I bought a dress there last year for my brothers wedding and I have to say they were superb, generally they will pick a few outfits to try on and will throw in a wildcard that you wouldn't have dreamt of picking out. I ended up buying the wildcard. They cater for all budgets too. I'm not associated with the shop in any way.
Ella Maries have gorgeous stuff but are outrageously expensive. My Mother bought an outfit in a shop up the country that was Eur600 cheaper than the exact same outfit in this shop.