Is there any validity to the belief of some in the sanctity of certain graves, making them preferable for burial over others, and is it permissible to purchase land for graves at exorbitant prices?

There are no graveyards preferred by Islamic law for burial due to their blessings or sanctity, apart from what has been reported in some narrations regarding the virtue of burial in Al-Baqi'. Some scholars recommend burial in Mecca, Medina, and Jerusalem, as well as near the graves of righteous people. Purchasing land to be a grave is permissible, but extravagance in doing so is disliked.