A construction manager just starting in private practice needs a van to carry crew and equipment. She can lease a used van for $2,700 per year, paid at the beginning of each year, in which case maintenance is provide. Alternatively, she can buy a used van for $5,010 and pay for maintenance herself. She expects to keep the van for three years at which time she could sell it for $1,600. What is the most she should pay for uniform annual maintenance to make it worthwhile to buy the van instead of leasing it, if her MARR is 20%?