Yes indeed. Ridiculously expensive. They all seem to be based around diode probes with various bits of black magic around them. Even looking at the construction of some of the probes, they seem to have a lot of stray inductance and capacitance around them and a hefty coupling capacitor up front. I'm going to leave this one on a big shrug.
Perhaps there is some mileage in the Tektronix sampling and differential probe designs which can be leveraged. A project for another day I think
