How to sell stuff at school? -

i already sell ps2 games and make money but i need to knw about other things maybe i can sell and if i need to raise my prices! i sell ps2 games for 3 dollars and movies for 2 dollars each! and im 13 and in eight if that helps any!

How about selling steel garnet necklaces, or just cheap necklaces that look expensive then sell them for about $2, or sell chewing gum and chocolate for $1 or 25c dependin on how much u want to charge, hope im of any help x