"working in perfect order" but it chews up discs?
I wouldn't consider paying anything more than 30% of new price for it if something is wrong with it (and yes, something IS wrong with it).
That is just me though. I RARELY buy anything used AND only if the price is right AND it actually is in perfect condition.
On the occasions that I do buy used equipment that is not in proper condition..........I am generally buying it for the parts (the price has to be pretty damned cheap though).
I would much rather go to my grave not needing my gun, than go there wishing I had it.