Before PE, I was making an equivalent of $86/hour gross (all in salary, bonus, and extra, no overtime position, I factored in all hours worked for a total of 2800). I expect to get around a 10% increase once I change positions as a result of the PE and nothing before that time. I'll be doing that in the next year or so.
PE makes you more marketable, indicates you are competent, helps you be retained, and is a point of personal pride.
As a side note, if PEs lobbied the state boards to restrict what non-PE engineers could do much more tightly the pay increase from being a PE would increase quite a bit more. An example of this is a physician. You can't practice medicine without being licensed. You can't practice medical specialties without being board certified. It's a heavily licensed and restricted sector.