From my experience, in the early 00's, getting pot in a public school was as easy as handing a 20 to the guy everybody knew sold it. It was literally easier to buy pot than a can of cola, as our school didn't have soda machines.

Alcohol? You could get a few cans of beer or maybe half a bottle of vodka, but anything more than that required a degree of planning or connections. Fairly easy, but nowhere near as easy as pot.