How much would it cost to create facebook?

[funny name]

Lets say Mark Zuckerburg didnt know anything about programming or designing how much would he have to pay a company to design and program it for him roughly? I know prices vary. Also after he paid for that company to finish programming and designing it would that company own a portion of the site? Will they continue to host if the site gets a lot of users? I know these are hypothetical but I have an idea for a website and I just want to know if its possible to get it down without knowing how to do it myself. Thanks for your help.