One of the country's poorest Native American tribes wants to buy a historically significant piece of land where 300 of their ancestors were killed, but tribal leaders say the nearly $4 million price tag for a property appraised at less than $7,000 is just too much.

James Czywczynski is trying to sell a 40-acre fraction of the Wounded Knee National Historic Landmark on the Pine Ridge Indian Reservation to the Oglala Sioux Tribe. The land sits adjacent to a gravesite where about 150 of the 300 Lakota men, women and children killed by the 7th Cavalry in 1890 are buried.

Czywczynski, whose family has owned the property since 1968, recently gave the tribe an ultimatum: purchase the land for $3.9 million or he will open up bidding to non-Native Americans. He said he has been trying to sell the land to the tribe for years...