I saw your pics and thought what a lovely specimen, though the price seems a bit steep.
Then I dug out slug-gun's recent ad for an Ackvoke at it was £220 in very nice condition but with a few marks/corrosion spots and a tiny bit of grip missing. But no pics, so it's impossible to make a direct comparison.
FWIW, my feeling is your pistol was priced for a boxed Ackvoke, so maybe the pistol alone is worth £100 less? This is just a guess and it may be that given its lovely condition, someone would pay more?