What was the black market at your school?

[Dwarfhamster]

pot. guns. knives. i bought a hunting knife of some guy for like ... $15 I think.

[Egomaniac]

Cigarettes.

Buy a pack and you could easily make 5-10 times what you paid just by selling single darts.

[Ashleyxoxo]

Nothing, we had our parents for money.

[Fencers]

Barrettes. It was a thing when I was in grade school to have ones with beads, bright colors, tassels, and various other eye-grabbing styles.

[Unlimited Power]

Only thing I recall is one troubled student who was stealing candy from a local supermarket during recess and selling it to other students for cheap.

Eventually he got caught and banned from the supermarket indefinitely.