From some WSJ article:

The setting of Einstein's initial salary at Princeton illustrates his humility and attitude toward wealth. According to "Albert Einstein: Creator & Rebel" by Banesh Hoffmann, (1972), the 1932 negotiations went as follows: "[Abraham] Flexner invited [Einstein] to name his own salary. A few days later Einstein wrote to suggest what, in view of his needs and . . . fame, he thought was a reasonable figure. Flexner was dismayed. . . . He could not possibly recruit outstanding American scholars at such a salary. . . . To Flexner, though perhaps not to Einstein, it was unthinkable [that other scholars' salaries would exceed Einstein's.] This being explained, Einstein reluctantly consented to a much higher figure, and he left the detailed negotiations to his wife."

The reasonable figure that Einstein suggested was the modest sum of $3,000 [about $46,800 in today's dollars]. Flexner upped it to $10,000 and offered Einstein an annual pension of $7,500, which he refused as "too generous," so it was reduced to $6,000. When the Institute hired a mathematician at an annual salary of $15,000, with an annual pension of $8,000, Einstein's compensation was increased to those amounts.