Prices range from $450 to $900 per hour ... minimum 7 hours, for a total of $3150 to $6300 for the "day".
If you're going on a day that's priced at $450/hr, something tells me that you probably don't need to pay for a tour.
Expensive but doable if you max out at the allowed 10 people, but gets incrementally more dear the smaller your group is. Theme park ticket is still on top of this.
I'm not sure the masses are using the VIP tours, but as
@PUSH indicated, maybe more are as they become aware of it.
My former boss did it a few years ago. She is worth 10's of millions, maybe hundreds of millions ... so again, not really a member of the masses. A common misconception is that you get immediate front of the line access, but she said they stood in FastPass lines (now LL, soon to be something else), so some waits were still in the 15 minute range.
All of this being said, if I had the money and nine friends chipping in, I'd do it in a heartbeat.