There's an AMD CPU in Airport; the iPod uses an ARM CPU. Some Macs have Intel gigabit ethernet chipsets (and maybe even USB). Intel makes a lot of other 'chips' aside from CPUs.
Do you realize how demanding it was for software manufactures to make the switch from OS 9 to OS X? Do you think Adobe, Macromedia, and Microsoft are going to jump at an opportunity to recompile all their software for X86 CPUs? Do you think people are going to repurchase all their software again for a new architecture? Do you think Mac users could actually tolerate any of the streaming hot, high power consuming, CPUs Intel or AMD has to offer? PPC is just fine.
As for expense, I don't know what price Apple has to lower themselves to before people quit whining. It seems like some people are just begging them to release a third-rate piece of garbage, which would end up harming their bottom line in the long run (remember the Performas?) If Apple released a $200 machine people would still bitch that some obscure Chinese reseller is offering blah blah blah, for $150.