From my experience...
Taken directly from the Rules of Golf
3-2. Prize Limits
a. General
An amateur golfer must not accept a prize (other than a symbolic prize) or prize voucher of retail value in excess of $750 or the equivalent, or such a lesser figure as may be decided by the USGA. This limit applies to the total prizes or prize vouchers received by an amateur golfer in any one competition or series of competitions.
Exception: A prize, including a cash prize, for a hole-in-one made while playing golf may exceed the above prize limit.
Also, the waiting period to get your amateur status back depends on how long you were a professional and how much money you have made. Typically, the limits are as follows, but there can always be an exception made by the committee for either a shorter or longer wait until reinstatement.
The money paid for reinstatement is payed to the USGA not the PGA.
I was a professional for 15 years, but for the last 7 I was a Division I coach, so when I applied for reinstatement, they considered my time as coaching time served and reinstated me immediately. Had I played in tournaments while coaching, this would not have been the case.
Hope this answered your question.
Mark