This reminds me of the time a friend and I went into a used game store, many years ago. We'd go there whenever we needed cheap NES games, which were usually 5 bucks.
On day I spotted a Tengen Tetris sitting on the shelf (this is back in the day when it was super-hard to find one, and when you did, they were bucks), and asked the clerk how much it is. Being not that bright, and not the owner, he goes into the back and asks. When he returns, he tells me it's 9.99. Sold, I say. I pay, we leave, passing the owner coming in as we are going out.
As we get into my car, in a panic pace of run comes the clerk, who knocks on the window of my engine-on and in-reverse car. My instinct... go! Go fast! My friend, he simply says, "Dude, if we go we can't come back for cheap NES games."
So I go back in and hear the guy's explaination of the mix-up and the wrong price. I give the thing back. All in the name of the moral high ground, and future cheap games.
Then, after all that, we never went back there. Ever. It's only known as the place of the 10 dollar Tengen Tetris... that I gave back.
Even funnier, we would have gone back, and bought many more games, out of both guilt and the giddy pleasure we had that day for getting something for a bargain. They would have had a lot more business in the long run.
Keep the damn discs, says I, man of questionable moral judgement.