As far as i know she's only available via an agency named Lourdes. In order to book her you need to sign up with them first, and you're required to pay a $1,000 retainer that acts as a deposit for your first booking. Her rate is around $2,500 an hour according to recent reviews (these are from about 3 months ago).
A guy in that forum said that he was required to book 2 appointments with other girls first to ask about Kourtney :KEKW: she must think she's the queen of England or some bullshit.