A licensed wholesaler may buy tax stamps, in the manner and at the time that the Comptroller requires by regulation. Tax stamps may not be bought from a person other than the Comptroller unless the buyer: has written permission from the Comptroller to do so; or is acting in accordance with the regulations of the Comptroller for stamping floor stock. The Comptroller shall allow a licensed wholesaler a discount of 0.82% of the purchase price of tax stamps.