Compared with the prices of an Aston Martin Vanquish Zagato, £250k for an Aeromax seems reasonable. The Aston Martins are listed from about £350k for what is a Vanquish with a few different body panels up to £750k for the estate version.
Some dealers have had these cars on their books for a very long time now and with a standard Vanquish round the £100k mark and a Vanquish S at around £130K - both of which look better to me than the Zagato version - I do wonder how long they will remain on the forecourt.