You really have to look at each class' unit plan. So for each lesson what are you teaching on that day? Look at the uni, what medium is it? That gives you an indication of what you will need.
Though my list isn't for art class, it will give you an idea of things you will need and can build up for your art department; "What is in an Artist's toolkit?
There are plenty of lesson plans on the net to show you how they look like, and depending on your curriculum requirements what you need to include. Start by backwards planning -what is the assessment outcome?
E.g Unit is Ceramics. Students need to make a Vessel.
30 students. Say 1x bag of clay gets 10 slabs, so 3bags as a minimum plus 2more to allow for stuff ups and just extra if there will be decoration.
Packs of Clay tools (comes with 12 usually, some 6 just depends on brand). So aim for a class set. Maybe 1 pack between two students if you are on a budget etc.
2x toogles (dont let them out of your sight as they go missing).
5-6 rolling pins (1per table + 1 for teacher)
Get a stack of cutlery from the op shop.
Get manual arts to cut some boards to desired size
Are you going to glaze or paint your ceramics??? Start off with a glaze...paint or slip can come later as the budget allows.
Aprons -class set
Lots of newspaper
Cling wrap & plastic bags to cover up clay between classes to keep moist etc.
Getting the picture?
Do a "shopping list". Look up your school art supplier brochure for ideas of what you need.