So anyway, I realized all this after I left the apple store, so ran to a nearby computer store and picked one up. At which point my friend told me there was already one in the laptop. D'oh!
The card is brand new, I opened the box but not the bag it came in but the receipt says you can only return stuff like this for the same item. So, I'm guessing there isn't a huge market for this, but anyone want to make an offer?
It was $49.99 at the store.