Nope, don't know about that one! But, Kleinfeld's has a HUGE selection so you could try there. Personally, I didn't love Kleinfeld's because a lot of the dresses just weren't my style but they carry a lot of designers and a lot of gorgeous dresses.
I think you might be talking about the Bridal Building, my boss actually JUST mentioned it to me, it's on Broadway and 38 or 37, google it. And if you do go to check it out, let me know how it goes, because I wanted to go to at some point!
I got my dress at RK, the sticker price was about $300 less than what it was in the other shops I tried it on in. Its definitely worth checking out, just get there early as they don't make appts in advance for trying on.
There is a Bridal Garden, which sells gently used (sometimes never worn) gowns for charity. It is not huge but they did have a really amazing selection. I think you can google Bridal Garden and find it.