The final purchaser of commercial equine feed, who has a dated receipt displaying the assessment added as a line item to the sale price, may by application in writing to the Board secure a refund in the amount added. The refund shall be payable when the application has been made to the Board within 60 days after the assessment. Interest shall be allowed and paid at the rate of 5% per annum upon the total amount of such assessment imposed by this Act, except when any such assessment is refunded within 90 days after an application for refund has been made within the required 60 days after assessment. Each application for a refund by a purchaser of commercial equine feed shall have attached thereto proof of assessment charged. A purchaser who obtains a refund is not eligible for any benefits provided under this Act.