In my opinion, $800 may be right at the top end or even high, for a Japanese bess or charleville in good condition (it would be a good price if a bayonet for the musket came with it); that price is more in keeping with a used, Pedersoli product. I know some fellow bought one for $1100.00..., but that just proves P.T. Barnum was right. Dixie offers the Charleville in a kit... for $40 more.
Folks out there on the internet think since the current factory produced muskets are so high priced, that a used copy, aka Japanese, is some sort of collector's copy. They forget, it's not Italian made, so was never proofed, there is no replacement parts source for them, and no manufacturer's warranty. If it doesn't have a bayonet, then you're looking at buying an Italian one, and having that adjusted, so that's $150+. Don't forget shipping on the musket and later, the bayonet.
Plus, like it our not, the Indian made muskets have made a huge dent in demand, so it's a buyer's market.
LD