Keep an eye on target.com, walmart.com, walgreens, office max, etc. You can find their local flyers online without having to subscribe to the paper. Over the course of the next 2 months, you should be able to get most of your supplies on sale. I have a friend who took her whole family (3 kids and hubby) to each store's school supply sale to get around the "limits." Costco has great looking backpacks and lunchboxes out already. For the last 2 years Toys R Us had a "buy a backpack, get a lunchbox free" deal.
I miss the bargain-shopping for school supplies. My kids go to private schools that ask for a check (~$100) for school supplies. It's convenient, but a very overpriced way to do it.