In terms of value this would destroy the value of existing machines. Even if there were 124 do you not think it was obvious to release a few at a time instead of showing your hand at the start?
I suspect that the number of people who'd like Spitfires to be relatively cheaply affordable massively outweighs the number who want to keep the prices high however.
More realistically, however well preserved they were, I can't help suspect that these Spitfires, however many there are in that hole, and however well preserved are not in exactly pristine condition. The protection put on them will have been designed to protect them for a couple of months or years in a warehouse, not 70 years buried under a tropical jungle.
G