The governing body of the county is hereby authorized to levy and impose, in lieu of the excise tax authorized to be levied in subdivision (3) of subsection (a) of Section 45-41-244.52, an excise tax on the storage, use, or other consumption in the county of any automotive vehicle, truck trailer, semitrailer, or house trailer required to be registered or licensed with the judge of probate of the county and purchased other than at wholesale outside the county for storage, use, or other consumption in the county as follows: Upon every person, firm, or corporation purchasing other than at wholesale outside the county any automotive vehicle, truck trailer, semitrailer, or house trailer required to be registered or licensed with the judge of probate of the county for use, storage, or other consumption within the county, there is hereby authorized to be levied, in lieu of the excise tax authorized to be levied in subdivision (3) of subsection (a) of Section 45-41-244.52, a tax in an amount not exceeding three-eighths of one percent of the purchase price; provided, however, that where any used automotive vehicle, truck trailer, semitrailer, or house trailer is taken in trade or in a series of trades as a credit or part payment on the sale of a new or used automotive vehicle, truck trailer, semitrailer, or house trailer, the tax authorized to be levied in this section shall be paid on the net difference, that is, the price of the new or used vehicle or trailer sold less the credit for the used vehicle or trailer taken in trade.