In all honsety, a STOCK exhaust, no matter how little it was used is only worth about $150 MAX.
Stock take-off parts are HARD to get rid of, there is not much of a demand for them at all, obviously, you didn't want it from the start, same as 99% of everyone else.
I have 7 or 8 BRAND NEW sets of exhaust, air cleaners, cylinders, pistons, heads and cams that I have been sitting on for several years becuase NO-ONE wants STOCK parts. I have been sending the cylinders out to get bored up to 95" with new pistons so I have "swap-out" big bore kits ready to go with no down-time waiting for parts.