A construction manager just starting in private practice needs a van to carry crew and equipment. She can lease a used van for $3867 per year, paid at the beginning of each year, in which case maintenance is provied. Alternatively, she can buy a used van for $6427 and pay for maintenance herself. She expects to keep the van for three years at which time she could sell it for $1251. 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%?