Those sales, exchanges, and gifts of trust or restricted lands specifically described in the following paragraphs (a), (b), (c), and (d) of this section may be negotiated; all other sales shall be by advertised sale, except as may be otherwise provided by the Secretary.

(a) Consideration not less than the appraised fair market value. Indian owners may, with the approval of the Secretary, negotiate a sale of and sell trust or restricted land for not less than the appraised fair market value:

(1) When the sale is to the United States, States, or political subdivisions thereof, or such other sale as may be for a public purpose;

(2) When the sale is to the tribe or another Indian; or

(3) When the Secretary determines it is impractical to advertise.

(b) Exchange at appraised fair market value. With the approval of the Secretary, Indian owners may exchange trust or restricted land, or a combination of such land and other things of value, for other lands or combinations of land and other things of value. The value of the consideration received by the Indian in the exchange must be at least substantially equal to the appraised fair market value of the consideration given by him.

(c) Sale to coowners. With the approval of the Secretary, Indian owners may negotiate a sale of and sell trust or restricted land to a coowner of that land. The consideration may be less than the appraised fair market value, if in the opinion of the Secretary there is a special relationship between the coowners or special circumstances exist.

(d) Gifts and conveyances for less than the appraised fair market value. With the approval of the Secretary, Indian owners may convey trust or restricted land, for less than the appraised fair market value or for no consideration when the prospective grantee is the owner's spouse, brother, sister, lineal ancestor of Indian blood or lineal descendant, or when some other special relationship exists between the grantor and grantee or special circumstances exist that in the opinion of the Secretary warrant the approval of the conveyance.