There are A4000's all the time on ebay, keep checking. I would highly advise the OP to ask the seller if the battery has been removed/replace and NOT buy it unless that has been done. If the battery has leaked, and it has at this point as it is over 10 years old, it would of damaged the RTC and possibly the SIMM slots. Even if it looks like "very minor" leakage! I bought two A4000s that looked like there was no leakage at all, but had some. RTC was dead. Had to repair traces.
Good luck!