Depends on what you need to them do, and how much they charge. Could be anywhere from a few 100 to a few thousand. If you find a guy on craigslist looking for barter his skills it's cheap, if you go to a real company that sets up pro sites you're looking at a big bill. Remember you need to setup a lot more than just a web page for people to get to. How will anyone know it's there? How will they order and pay for stuff? What about support for the systems? Licenses? You need a business plan first.