I think he got very large under-the-table payments for years. Educated guess by an Arkansan: the governor got one-third. Cummins cranked out 8,000 units a week (remember, this is plasma, not whole blood) at $50 or more per unit. Do the math. Speculation also had it that Hillary was the family money handler and that Vince Foster may have delivered cash from this operation to the Clintons.
I have speculated that Foster killed himself because of this scandal. He would have to cover it for them, and he couldn't live with it. Yes, I believe Vince probably killed himself --- on White House grounds. His body was then moved so that the FBI would not seal off his office as a crime scene.