N.B: I'm talking CDN dollars here...
It's certainly not $500 AND taxes, totalling $2,000.
Although I would like to minimize a loss when reselling a nib game that I've purchased, it's usually minimum $500 for a game that's still in production, and depending on how fast you want to move it, a little more from there.
I would say $600-$700 seems to be about the norm from my experience.
Personally, I think $300-400 should be the norm if it's still as good as the day you got it.
I also wish that recently unboxed nib games were available for sale more often. It's pretty rare that anyone has a chance to get a discount on a mint game that's a couple months old.
So supply and demand-wise, it should be very little since there's no supply.

Ask yourself this: if your supplier and a Pinsider we're both selling the same game in nearly identical shape, how much would you have to save to make a deal with the Pinsider, and not get the cardboard box?