oh, is that a very rarey in japan? will have keep an eye open on that then 
loose carts are usually in the 10,000yen range. cibbler is le 30,000 from the usual suspects.
This is a top 5 non-US release game for sure. When the repro is put in a famicom via an adapter, does it output with the extra sound capabilities?
Don't quote me but I do not believe so. It's complicated. Maybe someone here can explain better than I.
I can... sorta.
I assume you're talking about one of those in-cart bridge adapters that you can re-purpose into an all-purpose Famicom adaptor? I know that when you play games like Lagrange Point and Castlevania III through that adaptor, you won't hear any sounds from those chips. (you'll still get whatever the NES's internal chip is putting out, which isn't much)
Long story short, it won't work because the console's insides are different. While the Famicom's pinout has 2 pins for external audio, the NES's pinout does not. External sound cards were planned for the NES expansion port, and there are pins for that, but since they never made those... well there ya go.
I hear those repros are rumored to have workarounds for that issue, and I did see some further mods to adaptors that essentially create an auxiliary port for that sound. Pretty neat stuff, but tough to make from what I hear.
EDIT: Oh crap, I noticed you were talking about going the other way around, NES into Famicom... well it should be about the same story.
