I think the $7 JIS headset is all steel, whereas fancier headsets have some aluminum parts to keep them light weight. As I said, I've used it and it works great... the only real problem is it's low-zoot compared to something like a Chris King headset. Sheldon Brown's shop sells other JIS headsets also pretty cheap.

Before you go through all this trouble though, do try the ultra-ghetto method of headset adjustment