With rare exceptions, sticker prices at colleges go nowhere but up. In 2012, Sarah Lawrence College in New York crossed a threshold for tuition, fees, room and board that dozens of others have now topped: $60,000 a year. Sometime soon, prices will surpass $70,000. Factoring in books, plane tickets, other expenses and inflation, a student entering a private college or university this fall without any financial aid might spend more than $300,000 to obtain a bachelor’s degree.