On the trader, Toms car hasn't even been listed a week! So I don't think that justifies a comment as "not sold yet". If his car is still sitting there in 6 months time then yes, such a comment would be justified and should be noted in respect to the advertised price. Apart from GSF, cars hang around, whether that be an RCF, GTR, mustang, db9 or whatever, cars, houses or a table set on ebay.
As for an M4 for just above 20k? I think that we both must be on two different planets. Yes a 90k mileage cat D repaired 2014 model with 6 owners, but that is hardly a direct comparison the Toms RCF, do you know the spec, owners and history of Toms RCF?
At any one given time, there are 500+ m4 for sale, so different market conditions. However, for an m4 of the same year, similar mileage and NON CAT, you are starting at £27,000 all day long and this is not even looking at the equivalent spec, of which if you jump back on the trader, you will see that the standard RCF prices are around that figure.
Reference your opinion on the halfords carbon, that is your opinion, unfortunately for both you and I, opinions don't count when it comes to a valuation but facts do and the facts are the carbon edition is more rare than a none carbon, making it more exclusive than a none carbon. From factory the carbon costs, as standard, 7k more. That fact cannot be hidden nor dismissed.
Based upon what is on the trader right now, the screen price of Toms car is quite clearly correct. Any lower and he is competing with RCFs that are not only of a lower spec, but also higher mileage. Really? Who would do that?