I recently bought an old G3 ibook off of ebay as a backup if my other laptop fails. It was very cheap, under $200, but no airport card. I really wanted one of those nice usb wi-fi adapters, but most I found didn’t support OSX. Well, in case you are every looking, I found one - Asus/Addlogix WL-167g USB 2.0 Wireless WLAN Ad. You might be able to find one of ebay cheaper.