I have #3 starting this year plus our school changed to a new uniform so we had a lot of expense this year.

Shoes $200
Shirts $189 (9 shirts)
Shorts $60 (boys shorts changed from grey to navy so even though his old ones were fine, I had to get new ones)
Skorts for DD2 $50
Stationery $100 (enough to last the entire year)
Drink bottles $90 (stainless steel ones - never buying plastic ones again is the plan)
Hat for DD2 $15

And of course come winter I will have winter uniform expenses too.

It is a lot, but I have actually found that I don't have to buy as much casual clothes for when they are home as they are at school most of the time kwim? So I suppose it all evens out in the end.