This dude got the deal of a lifetime , and he did it completely by accident. One day, this guy went to wander around a big box hardware store to check out their lawnmowers. When you're making a big purchase like that, it helps to see the machines in person, instead of just relying on the internet. This guy found an especially great deal, because the store's display lawn mower was up for sale. As with lots of big purchases, usually you have to check out several stores and be prepared before buyi…