There are a few little hole in the wall sex stores on 8th avenue mostly (and some on Christopher street) that will sell off-brand names and sometimes things like Andrew Christian and C-IN2. There's also TAGG still on 8th in Hell's Kitchen, which sells a lot of brands (but if you want thongs, they only carry their own, which have pretty much no space for your bulge at all). It's not what it used to be :(