Just did the math (based on 2012 revenue and reported # of employees), and yup, $600k is what Google could easily afford for a single employee (with a good $400k left over for business expenses, per employee).
It's not a tight bound, I used a general rule of thumb that a fully loaded employee is 2x their base compensation. A good google engineer can easily earn $200+k per year in salary + bonus + stock. Obviously the 2x rule of thumb doesn't scale as health care, insurance, and other costs don't scale up, but I'd estimate that given the perks at Google, there's at least another $50-100k overhead. So realistically, it's probably 2 seasoned engineers, or 2 seasoned engineers plus a fresh graduate.
