From: Rabbi Moshe Sofer
To: Rabbi Wolf
The orphans of R. Peretz of Trentshin paid eight hundred gold coins to the Pressburg Chevra Kadisha for a premium burial plot near distinguished community members. The Chasam Sofer rules that the transaction was legally valid since ona'ah does not apply to land transactions and the purchase was voluntary, but negotiated a moral compromise whereby the Chevra Kadisha returned two hundred gold coins out of concern for the minor orphans' share of the estate.
Source: Shu"t Chasam Sofer YD §330