Recently, the "L" key broke. Happily there are several places to buy keys and attachment mechanisms for prices ranging from $5 (refurb key, probably just fine) to $9 (key and hinge) to $20 (key and hinge, never used, Apple) to varying prices up to $100 + shipping for a new keyboard. I opted for a used keyboard for $26 (incl. shipping) from Mac Recycling (see update)...
I chose the used keyboard option since the old one is a real mess, infested with generations of dog hair and varied unmentionables. I'm sure other keys are going to break. If the replacement kb works I'll have a supply of two of each keys, excepting the "L" key of course. A wonderfully obsessive web page tells us how to disassemble and clean an iBook's keyboard, so I feel reasonably prepared. (A few days later the site disappeared! This alternate guide is excellent.)
The prices per key do explain why even broken iBooks have some value to resellers. It's a real win-win; I'm quite happy to pay $5 for a working refurbished key and that means an old but relatively clean iBook keyboard is worth something. When this machine finally dies, (lord knows when, it seems it might go on for years) I'll cast around to see if anyone wants to pay shipping fees to get the relic and its working Airport card.Update 7/7/07: The Mac Recycling (macrecycling.com) keyboard arrived with one key off and a kink in one side. I was angry at first, figuring they'd sent me a bum keyboard. On closer inspection though I see that the FedEx shipped box is creased along one edge. I think the keyboard was probably fine when it left Mac Recycling, but they might have done a better job packing it.
Thanks to some manuals I downloaded from the superb PowerBookMedic site I was able to replace the dislodged shift key and install the keyboard; so far it works though one top tab didn't quite fit and I had to press in the side where it had been kinked. In any case it's firmly in place.
Next time though I'll go with either PowerBookMedic or iFixit.com; I owe them for the excellent repair books they provide. I recommend downloading the one that fits your laptop and keeping it at hand.
Update 7/18/07: Mac Recycling (macrecycling.com) did not respond to the message I left on their web site. Email isn't as reliable as it once was, so there's a 10% chance they're not crooks. Unfortunately, there's a 90% chance they are crooks. Don't have anything to do with them.