I think the values quoted are a bit high. Very nice carbine though.
Check some of the known dealers in antique arms. I just looked at a couple online, and decent carbines can be had for much less then $6k. Very good Buffalo Sharps can be had for much less than that. That doesn't detract from your gun, just be realistic in expectations.
"Far better it is to dare mighty things, to win glorious triumphs even though checkered by failure, than to rank with those poor spirits who neither enjoy nor suffer much because they live in the gray twilight that knows neither victory nor defeat." -Theodore Roosevelt-