How does GS profit work on a game they deem as used?
you just have to look at how acquisition and sale works.
they acquire a game from place A for price X.
they then sell game to a customer for price X * Y% (markup)
for a new game
A = publisher
X = wholesale cost to publisher
Y = MSRP / wholesale_cost (margin)
for a used game
A = trade-in customer
X = trade-in value
Y = desired margin (usually 150-160% markup)
in this case
A = Nintendo
X = here is where it gets sketchy. either this is going to be wholesale cost to nintendo, or licensing costs plus manufacturing/distribution costs if GameStop is in fact the distributor for the game.
Y = $90
So being a trade-in or new game doesn't affect "what percentage" gamestop gets. They simply buy all of their games for a price either from customers or publishers, and then sell games for a price, either MSRP, discount/sale price, or market value.
I think it's just a question of image. They COULD sell new copies for $90, but that would look really shady. By pretending they're used, most costumer can assume it's a very hard to find game that they were lucky to find somewhere. Super-hardcore gamers on Neogaf know it's a disguised reprint, but most other costumers won't have a clue.
eh, I really don't think it's anywhere near as shady as that. The more likely scenario is that there are pricing laws in some state somewhere dictating some sort of thing, or offering price matching/protection, etc. There are also credit cards that offer similar protection.. So if Gamestop offered it "New" for $90, a lot of credit cards, if you can find a listing online for $50 but out of stock, the credit card will still match like-kind and chargeback the difference to gamestop, etc.
Selling them used is probably more about legally CYA with various consumer protection laws/practices than actually trying to deceive anyone. Just my guess.
edit - in regards to the above, if that's the case, designating new/used isn't really any shadier than like electronics manufacturers designating a model going to Sears as AXH-1000S and a model going to Best Buy as AXH-1000B to prevent price matching, something they've been doing for decades. Or manufacturing the exact same product under different subsidiary companies and stocking them at different stores to accomplish the same thing.