I originally found the dress at RK Bridal in NYC. However, my consultant sucked and it was like the Home Depot of dresses, so I didn't want to buy from them. I ended up purchasing from BestBridalPrices.com which is an authorized salon in the midwest that also sells gowns online. I ended up paying about $1k and they threw in a veil too. They were really nice and pleasant to deal with. I just found out last night that I forgot to put in the order for my veil, and they're going to let me do it even though it's a few months later!
If you want to try the dress on, Ida's Bridal in Torrington has a sample size 12 of the Edimburgo. I'm not sure how much they're selling the dress for, but I think they might have other San Patrick gowns as well. They were pretty nice.