I've seen these bought (Buy it now) for upwards of $499 on eBay. To garner the top dollar you need to do the following.
1) Show the original box, disks, keyboard, mouse, and a least one doc. Power cord is key.
2) Show in pictures that the case has no pry marks and no yellowing. Put it side by side with a newer G3 beige if you have to, to show no yellowing.
3) Have finder 1.1g on original disk and running in the pics.
4) Mac designer Burell Smith favorite version of defender doesn't hurt to have. See "Insanely great story: Revolution in the Valley Show in pictures that the case has no pry marks.
5) Be the original good owner. i.e. show the 4.5V battery is perfectly maintained.