A Wolf has the same basic shape as a standard Land Rover, but there are very few parts which are the same. It's is built on a completely different chassis, with a 300tdi engine, R380 gearbox. The axles are different, as are the springs and shock absorbers. The rear tub is very different and it has a special roll cage fitted, even the front wings are different. Electrics are all 24v, so different starter, alternator, wiring looms etc to a standard Land Rover.
They are expensive because there are relativley few in private hands, and they rarely come up for sale. The price seems to keep climbing as more people want them but no more are released. Those which you do see for sale are all accident damaged rebuilds. Having tried to rebuild mine to a good standard, the time and effort required, not to mention cost of the new parts soon adds up.... and that's providing you can find a rebuildable wreck which is cheap enough. The last few wrecked 90s through Withams were close to £10,000 and that's before you start with the new parts.
Chris