They bought this car for £42k from a dealer who didn't know what they had. Almost everyone knows this, and that's one of the reasons (there may be more) it's not selling...
What the dealer bought the car for is irrelevant. I would imagine there are some sour grapes because they am have bought it well; however, they took the chance and paid their money for it, so good luck to them.
£52k for an S3 Aero 8 is market value IMHO.
A mint S1 is near £40 (average ones are circa £36k), S2s are in the £40s (again mileage, condition, history and colour dictate where in the 40s) and S3s are falling into the £50s. Following on from that, the last of the Aeros (S4) are still holding strong in the £60s.
I wish Morgan hadn't stopped Aero production BUT the effect the decision has had on residual value has been a positive for owners.