cartweaver, is the one we started with . any one you get pre built will definlty need to be customized, theres no getting around it. hiding price to public is not a feature of any prebuilt shoppping cart. paying on an account, and acccount tracking of those sorts. are modules you need to build in.
we built a wholesale website, i looked with your same intentions. and i can tell you thats what i found after alot of research. if you do find something prove me wrong! no one can build a cart with every complete intention in mind