I think Conrad's in Tudor City sells BMCs, the guys has always been a really decent cat to deal with, and they don't do any low-end stuff. I haven't bought a full bike there, but it's near work for me, and they've been really helpful with stuff both for my newer bike as well as my beater.
Don't know City bicycles. SBR (
www.sbrshop.com, the store is located on 57th or 58th street) also has BMCs, they'd be worth a try as well. Conrad's (42nd Streetish, Tudor City Place, just east of 1st ave.) seems to have a focus on custom spec'ed bikes, and they don't have pre-built stuff in the store that I've ever seen.