The Mark King basses are quite nice and the electronics package on the MK Signature Deluxe is the closest thing you can get to a Series bass. The price you quoted seems really high to me, though, especially if it isn't the Mark King five-string with a Balance K Omega body shape, youshould be able to find a used Series bass for that price. Unfortunately finding a used Series bass with the Balance K shape is difficult since it is a more recent model. Do you know the serial number of the MK bass you are considering, does it have LEDs? If it is one of the older ones the price is definitely high. If your budget allows you to even consider a $9,500 bass, I think you could find a used MK Signature Deluxe five-string with LEDs, Cocobolo top and Balance K Omega body for less than that. That kind of budget really expands your options.
Good luck with the search!