So why are they all so expensive ? And why aren't there a bunch of mid range knock off's for $100s of $ rather than into the $1000 s ?
Measuring capacitance and inductance or impedance results are tightly related with frequency.
Most low end hand held are merely max out from 100 Hz up 100 Kilo Hz.
High end ones usually can do scanning from few Hz up to Mega Hertz range, and able to scan the DUT's impedance profile, this feature it self made these high ends differ from cheap handhelds.
An example capacitance result from 4 digits priced LCR meter, courtesy of The Electrician.