Only 3 events Boo - Campaign doesn't count towards NPPL, but that aside, you're right...selling an NPPL Pro spot off at the end of the season could make some teams enough cash to play all next season on in Div 1, and pick up some really good players.
Team X just scrapes into the top 18 and loses its two star players to Infamous and Oakland, so the captain sells his spot to, say, Gary Shows for arguments sake, drops down a division and rebuilds with the finances to attract great players and offer a free ride..nice long term building strategy for a young team.