What makes you think a brick and mortar store would be any different? In my opinion, it would be harder!
You're then competing directly with the likes of GAME and GameStation (as well as the other high-street stores stocking games, and there are lots). Selling at a better price isn't going to guarantee you success either, the over-heads are a lot higher than selling online. You still need to sell in volume too, which isn't going to be easy. Unless you have a store in a prime location (which doesn't come cheap!).
I think your time and money would go further if invested elsewhere. Sorry to be so negative, but better to figure this out now than later down the line.