I have bought a lot of kids gear used on Ebay for good bargains. When PathfinderJR was little, I used to buy cheap stuff because I knew he was going to outgrow it all in like, 5 minutes. He tells me now (he's 22 now) that often he was miserable. His little brother is 8 years younger than him, so when Little Pathfinder started hunting, JR insisted that we buy him "good" gear. He promised that whatever I bought that LP outgrew, we could resell on Ebay and recover enough that it would be no less expensive than cheap gear would have been. So I bought him Sitka, Kryptek, etc... When he outgrows it, we resell it and recover much of the cost. Someone gets a good deal on gear that is lightly used, and we have some cash to turn around and buy some more stuff that fits. Sitka has always had a good line of youth-sized gear and much of it isn't nearly as expensive as you think.
As was mentioned earlier, watch for when your kids get to be the size that women's sized adult gear will fit them. Lots of good deals on used women's Kenetreks on Ebay.
