Hmm... not necessarily true... as long as it is retail version, and CD-KEY then he should be ok. Just ensure the CD has the Holigraphic images for win2k, and the Orange Sticker, and that the sticker serial number (cd-KEY) actually works for that version of CD...

I have seen many sealed authentic M$ CDs with Orange stickers for sale at markets etc...

Now, since it is only win2k, i wouldnt pay more than 30-50 dollars, as you are better off buying a Microsoft Mouse or Keyboard, then purchasing Microsoft XP with SP2 OEM for just over a hundred