Really the question I have is why would anybody NOT buy a mac? What benefit do Windows or Linux offer (for a user/developer machine!!! (not server))?
Can you buy a netbook with OS X on it? How about a thin and light laptop with an excellent keyboard, or an expandable desktop that doesn't cost at last $2.4k.
OS X is a great operating system, but it also locks you in to Apple's very limited choices for hardware.
I have a theory that it's impossible to prove anything, but I can't prove it.