You only need 10 sets to start a club. The total cost should be about $200.
Remember that this is a club for getting students interested in chess. There is no need to make it very formal or advanced. You will learn the rope along the growth of the club. When the club grows to 30 or more students, you may want to introduce formal instructions in another setting for those serious players.
Read the long manual "A GUIDE TO SCHOLASTIC CHESS" from USCF: