I did a search on this machine on eBay, for completed listings:
http://www.ebay.com/sch/Sewing-Fabri...mplete=1&rt=nc
One sold for $495 (gone over by a technician), and one for $395. I would think that $500 is the top used price she could ask. I would offer less, citing the potential problem with getting replacement parts in the future. In my opinion, $500 is a fair price but so is $400. The machine is quite old, but absolutely fabulous when it first came out. I took a class from Susan Cleveland years ago --
http://www.piecesbewithyou.com/ -- and this was the machine she had. She raved about it at the time, said it did everything she wanted it to do, and said she never planned to buy another machine. Don't know if this is the machine she still uses for her work now, though. Somehow, I doubt it. Bet she still has it for a backup machine, though.