A club will pay what they think they're worth, yes, but clubs will always try and pay the lowest fee they can.
Tanto and Pye with one year left on their contracts with the threat of leaving for free next summer leaves County with a weaker negotiation position than them both with three years left.
That stronger position County are now in will almost certainly put some (not all) clubs off a deal that could have been struck for less.
I'm not saying they'll both see out their new deals, they may even go in January if they have great starts to next season, but I'm fairly confident that there's little chance of either leaving this summer.