And as if by magic, today's car boot bargain was another iMac G4, the 20" model, in very good nick and including an Airport Extreme wifi card - for a tenner!
It nearly did my back in getting it to the bus stop and home, but fortunately it's all one route so the actual journey was easy enough. Just in the throes of putting OS X 10.5 on it, which is the best way I know to ensure everything works, after which I might think about adding more RAM (it can theoretically take 2gb, currently .75gb) and shoving in the spare 320gb hard drive I've got knocking about somewhere. It may also need a PRAM battery and other maintenance. But with a bit of work it ought to sell for £100+ (if I don't succumb to the urge to keep it as my own retro-tech) and I am VERY pleased.