Just popped this on eBay:

Brand new US-layout keyboard for 15" PowerBook, backlit models. 
Originally intended for my G4 1.25GHz, but the computer suffered a trip 
and has been replaced with a 2.2GHz MacBook Pro (I think I'd have 
preferred a MacBook!).

Also included are the OS disks, box, video leads, direct plug connection 
and manuals for the aforementioned PowerBook 1.25 GHz.

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&rd=1&item=320185637340

Listing is here - note the "Make Offer" function. I already dropped the 
price a tenner because no-one was looking, but the keyboard is $99-159 
depending on where you look online. And yes, you can pop the keys off 
and swap them, but not ALL of them, because this is a US layout 
keyboard. Finding UK ones is very hard, or was when I wanted one.

Richard

I'm also considering massively reducing my collection of old Macs, since 
I'm probably going to be moving to a smaller, more "civilised" sort of 
house and location. Still want a Mac IIx though, which is probably daft.