Don't forget to check the bottom of the CPU to make sure that all the
bits are present and accounted for and there are no scratches on the
pads or mis-aligned capacitors (potentially dangerous) all of which are
common problems with used CPU's.
Used 6386SE goes for around $150-250, I wouldn't pay more and I wouldn't
get one that is damaged or has the missing capacitor issue (what the
hell are these ebay guys doing with their CPU's?!??!)