Talking to the Nottingham Evening Post on Monday, Derry said "Simon King has just gone from Barnet to Gillingham for £200,000 and I don't think he is anywhere near as good Bap,".
"There is also the fact he has played more than 150 games for the club, is younger than King at 21 and is more versatile.
"All those factors means Bap has to be worth £300,000 in today's market."
"Realistically, I think it would have to be someone in the Championship who signs Bap, but I want to reiterate that we don't want him to go.
"I think it would give us the impetus to push forward in the new season."
The price was rumoured to be in the region of £250,000, with that figure alone enough to put Crewe off from pursuing their interest in the Stags defender.