I would quibble a bit with the "estimated value" part. A thing is only worth what someone will pay for it and as nice as the PW Limo is, they're not heavily collectible. There are enthusiasts out there but the number of PW enthusiasts who actually have 100k to spend and actually would pay $100k for something they didn't restore themselves are so small as to be effectively nonexistent.
Keep in mind that the "classic" Power Wagon was sold in the US in more or less the same configuration from 1946 until 1968. Overseas production ended in the early 70's (1972, IIRC.) My point being that these "classic" Power Wagons are not excessively rare. I can think of at least half a dozen I've seen in recent months in and around Denver.
The military cousin of the PW, the M37 series of vehicles, is even more common than the PW.
For those interested in PWs, there is (or was) a magazine actually dedicated to them: Power Wagon Advertiser, published in Iowa.
The M600 series of military vehicles are somewhat rare but they turn up occasionally. They were militarized versions of the post-WWII Civilian PW that were marketed exclusively for export to other countries (the US military never used any of the M600 series vehicles.) I have seen photos of ambulance versions, carryall versions and pickups with soft tops, similar to the M37 but distinct in a number of different ways.
(Note: I owned a 1952 M-43 ambulance, the ambulance variant of the M37, from 1993 to 1995, which is how I got "into" Power Wagons.)