No it's not an error, unfortunately. The market is very quick to react to a limited-run, niche book going out of print and the used price seems to be amplified by the more 'living history' that is involved i.e. how many connections there are to veterans today.
Other examples are Crowood's "Slingsby Sailplanes", about £70, or Peter Morton's "Fire across the Desert" about Woomera, £300+
I managed to bag a copy of the latter for £50 in a second-hand bookshop, stupendous amount of money for some old paper but presumably mis-priced and I held it close to my chest all the way to the till in case someone else tried to pounce on it.