If he leases.
$600 (for security deposit) + (450 x 36) for closed end lease
$600 + $16,200
Lease cost = 16,800
If he buys.
$2,400 (for down payment) + (515 x 36) for closed end lease + 1,080 (for 6% tax)
$2,400 + $18,540 + $1,080 = $22,020
Purchase cost = $22,020
After selling at the residual value of $6,500
Purchase cost minus Residual value
$22,020 - $6,500
=$15,520
So, if he leases he will not be able to have the residual value and he'll be spending more than if he buys. he'll actually be making a loss of $1,280.
Final thought: HE SHOULD BUY!