I would say that a used iBook G4, last revision, would not be worth more than $500 in stock configuration. If they can afford the extra few hundred dollars, I would strongly suggest a used (can be found for between $600 and $900) or refurbished MacBook (around $1000).
I have a used one I'll be looking to sell just after christmas.
Specs are :
All install discs, powercord, & original packaging
*Brand new keyboard (1 month old), as the old one had a key that wasn't functioning properly
Everything works great and my wife hasn't had any problems with it in the 2.5 years she's had it. Battery still lasts a good 3+ hours. I'd be willing to let it go for around $425+ship. This is the last model before they released the macbooks. If you go with a macbook, stay away from the CoreDuo models, they had a ton of problems initially with those (ran hot) and you don't want to get stuck with a lemon.
I've sold maybe 20 items on here, shipped across canada with zero problems. I can supply pics if you're interested.