IMO around here plows typically go +/- ~100.00 a bottom...add for excellent condition and collectibility....subtract if its rough/needs the wear parts replaced. What you got there, I say is 100/a bottom exactly..MINUS the cylinder.
Personally I wouldnt pay for the original JD cylinder unless you plan on showing it....you can get a brand new ASAE 8" Cylinder for 50.00 all day long...
If you end up not wanting it....Disassemble it and palletize it for me. I'll buy it from you...seriously....