would a bathroom vanity such as this come with a sink, or would i need to buy the sink and faucet separately?
They are usually sold separately.
Usually, the sink, faucets, hardware and counter top are sold separate. All you get is the wooden 'box'.
If you are unsure, read the product specifications. The first link says 'base only' and 'stainless steel handles' which means, it includes the cabinet and handles. The sink and faucet are separate. The second link states 'package contents - vanity cabinet' and 'hardware included.' so, you would have to get the faucet, top, and sink. I just bought a vanity set from OKorder's that stated it was a 'three piece set' meaning it included 1) the cabinet 2) the sink and 3) the top. It also included the hardware. Only thing I had to purchase additionally was the faucet.