Massallah pertaining to a business transaction

assala mu alaikum
i need to purchase a commodity for my business but do not have the funds
a muslim person has the funds but wants a profit on the transaction
the commodity cost R6800.00 a ton i am willing to pay him R200.00 a ton
R6800.00 X 70 = R 476 000.00
200.00 x 70 = 14 000.00
how can we structure this transaction islamically i would pay him R490 000.00
in instalments over four months
salaams