Mansfield have put a �300,000 valuation on Alex John-Baptiste, 21, whose move to Crewe recently collapsed. The defender is out of contract, but the Stags are entitled to compensation if he moves because he is under 24.
However, if nothing is agreed between the clubs, the fee would then be settled by a tribunal.
"Simon King has just gone from Barnet to Gillingham for �200,000 - I don't think he is anywhere near as good as Bap," Stags chairman James Derry said.
"He has also 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."