I may be off a bit but those empty carts aren't worth much even on the Super Famicom. The value mostly comes from what should or could be on it. A blank could net you a hundred or two USD, but throw something say like a published game, it can add a little to a lot, and if it's a beta of a game a bit more, and popularity (say Chrono Trigger vs Hyperzone) adds more yet. Best would be a beta of a game with a big change or a proto of something never released (like that white whale of an unreleased Wing Commander 2 that got finished and lot PONY created.) I'd probably start it at a couple hundred bucks and let people battle, or put a $500 price and take whatever best offer even if it ends up being like $150.

That gold cart though, you're nuts. $2400aud is $1800 US, and I don't recall seeing that one come up often but when it does it has sold for hundreds less, closer to 1000 than 2000.