After a sufficient appropriation for the purchase of firefighting apparatus and equipment, including housing, is made and is available, the participating units, with the approval of the fiscal body of each participating unit, may purchase the firefighting apparatus and equipment for the territory on an installment conditional sale or mortgage contract running for a period not exceeding:
The purchase shall be amortized in equal or approximately equal installments payable on January 1 and July 1 each year.
IC 36-8-19-8.7