That's an average of £545 per pax. Good job the CAA are not running an airline.
It does sound like a lot, but you would have to think that finding this amount of capacity at such short notice doesn't come cheap.
Presumably the operators providing this capacity will have also factored in empty leg/positioning costs to get the aircraft to and from where they're needed.
It seems that there has been some consolidation going on, for example, I understand that Wamos operated into MAN yesterday, with pax that originally departed from BHX and LBA being bussed to their original starting point.