§ 718b. Sales; fund disposition; unsold stamps
(a)
 Sales 
(1)
 In general 
The stamps required under section 
718a of this title shall be sold by the Postal Service and may be sold by the Department of the Interior, pursuant to regulations promulgated jointly by the Postal Service and the Secretary, at—
(2)
 Proceeds 
The funds received from the sale of stamps under this subchapter by the Department of the Interior shall be deposited in the Migratory Bird Conservation Fund in accordance with section 
718d of this title.
(3)
 Minimum and maximum values 
Except as provided in subsection (b), the Postal Service shall collect the full face value of each stamp sold under this section for the applicable hunting year.
(4)
 Validity 
No stamp sold under this subchapter shall be valid under any circumstances to authorize the taking of migratory waterfowl except—
(5)
 Unused stamps 
(A)
 Definition of retail dealer 
In this paragraph, the term “retail dealer” means—
(B)
 Redemption of unused stamps 
The Department of the Interior, pursuant to regulations promulgated by the Secretary, shall provide for the redemption, on or before the 30th day of June of each year, of unused stamps issued for the year under this subchapter that—
(b)
 Cost of stamps 
               	 	
               	 	
The Postal Service shall collect $10.00 for each stamp sold under the provisions of this section for hunting years 1987 and 1988, $12.50 for hunting years 1989 and 1990, and $15.00 for each hunting year thereafter, if the Secretary determines, at any time before February 1 of the calendar year in which such hunting year begins, that all sums in the Migratory Bird Conservation Fund available for obligation and attributable to—
(1)
amounts appropriated pursuant to this subchapter for the fiscal year ending in the immediately preceding calendar year; and
have been obligated for expenditure.