I can see how back to school can get expensive fast! Especially with activities/sports that start up again and as the kids get older, they need more supplies or have more projects they have to work on that cost more money. Plus, often, they grow out of their entire wardrobe from the year before!
DS is starting Kindergarten this year. They sent a supply list in the mail for items they are asking each student to provide. It doesn't have a huge amount on it but it is very specific regarding brands and items. I've got about half of it so far, was waiting for back to school sales but will probably pick up the rest this week so I don't have to worry about it later (after I have the baby).
I did pick up some clearance clothing for DS at the end of last winter but not much . . . he has some jeans and some long sleeved tees but has grown out of everything from last year. It doesn't get cold here till November, sometimes not till the end of November, so unless I see a great deal, I don't plan to buy him much in the near future. I will sort his clothes from last year though and sell anything worth selling on ebay so that I can use the money to buy things he needs for this year.
My mom likes to take him back to school shopping. She takes him on a special outing, just the two of them, lets him pick an outfit or two, some school supplies and takes him to lunch. She has done this the past 2 years for preschool and said she wants to do it again for him this year too. She says that she wants that to be something she does with each of her grandkids every year. It's a nice thing for us too! She always asks if there is anything specific he needs.
I bought his backpack and lunch box last week. Spent a little more than usual but this one should hold up much better than the cheapies I've been buying that don't even last the school year.
One concern I do have is the activities side of things. He has already mentioned wanting to play soccer and take karate. The soccer team doesn't cost much and the karate classes are affordable but it's the extras that start to add up with that kind of stuff! For soccer, he'll need cleats, knee guards, the team socks and shirt. For karate, he'll need the uniform (though the school I talked to said it's not something you have to buy right away, let him try it out first for a bit to make sure he likes it before purchasing any equipment or uniforms.) But it's all those things that add up!