Well, I would think it would be worth $600 anyhow. That buy it now price seems pretty high, they usually are. Not a gun that you see for sale every day, so it's hard to put a number on. Keep an eye on that one and see what it goes for, that will give you a better idea of the guns true value.
Also there is a small round wire clip that fits around the breech plug and holds the primer in place. Where the heck can I find one of these?
I see other manufacturers use a similar set up but I can’t find just the clip.