School supplies = Go to walmart and get them $35 should cover the entire year
Toys = $300 a year tops ($200 of which is dedicated to a single big gift such as a bike or ps3)
Furniture = Second hand stores
Clothing = no name brands
As for the traveling supplies, kids outgrow them so quickly it's very easy to find used ones for less than half the cost of new ones.
Then again I grew up in a low income household so I am relatively accustom to knowing how to get the most for my $ without frivolous spending.