It was $15 by the early 70's.
Then I learned a lesson in politics and economics.
One night, a lid was $15 Mexican pot.  During the night their was a huge 
combined raid on Mexican pot farms, spraying the plants with paracuat, which 
made the pot unusable.
The next morning their were lids a plenty, but they were $20 Columbian.
The more the efforts to restrict the supply of pot, the more money money was 
made by the dealers and distributers.
Prohibition gave us organized crime, the "war on drugs" has given us the 
drug cartels.

Those who will not learn from history are given another chance to learn the 
same lesson.