John has an investment opportunity that promises to pay him $18,500 in four years. He could earn a 4% annual return investing his money elsewhere. (FV of $1, PV of $1, FVA of $1, PVA of $1, FVAD of $1 and PVAD of $1) (Use appropriate factor(s) from the tables provided.) What is the maximum amount he would be willing to invest in this opportunity?