In my opinion, "older" titles like ACDC and Metallica etc are worth every penny that a new GoT Premium is. In fact, odds are that ACDC and Met will likely be viewed as better games in the long run (simply guessing as GoT would have to be amazing to rank up there with these other two). Since you can't find either Met or ACDC NIB anywhere, why wouldn't they be worth as much as a current priced NIB?
I was concerned about the exchange rate when I bought a TWD recently. The thing is, I expect that its value would drop if/when the currencies even out. BUT... if that's the case, you'll still be able to sell TWD at or near whatever the then current price of a Premium is.
So I expect if the game is killer and really well rated, you should always be able to get the same price as a NIB -providing your pin is in immaculate shape.
The fact is, if you want an ACDC or Metallica right now, check out the cost from the States. Plus, you likely don't get to see it before buying, might have to send cash to someone you don't know, and/or put in a lot of time driving to get it. Shipping/gas etc add to the price and there doesn't seem to be any way to avoid full taxes at the border so apples to apples, ACDC and Met should still be worth as much as other options -in my opinion.
This works in the other way too though -if the US dollar was at par with the Canadian dollar, TWD is no longer worth today's prices because you could get another Premium NIB for 30% less.
So bottom line for me is that the best Stern pins out there should be worth current NIB prices and will fluctuate with the exchange.
If they're not, and you have a Premium or LE Metallica for sale at a really low price, let me know!