Hello Julian, to me it sounds over priced. Is this from a dealer?
A couple of years back I bought a user IIIf Black Dial in good condition off this web site for $275. A good looking and well functioning camera, but one that had seen some considerable use.
My current IIIf RD/ST, the last version of the IIIf is flawless and barely used. From a seller that was uninterested in photography. I was able to purchase it, with the last version of the Elmar 50/3.5 mounted for $375. It needed a full CLA, as it had been sitting for decades according to the seller and she was correct.
My IIIg, which also needed a CLA was only $500 US. It's has a couple marks from the Metrolux meter being installed and removed.