While driving home today (3 October 2001) I heard an NPR radio interview
with a UN drug official.  The points made:
1) the Taliban ban on growing opium was enforced
2) stockpiles of opium allowed Afghanistan to continue to be a major
supplier of opium
3) in the week after the 11 September tragedy the Taliban, apparently
wanting to raise cash, dumped so much opium on the market that the price
fell from $700/kilo to $90/kilo.

As I was listening while driving, I am not sure where these prices
prevailed, inside or outside Afghanistan.