I know it sounds terrible but last year when I THOUGHT I bought a PS3 bundle, it wasn't until Monday a few days later that I realized we didn't pay for the PS3 because the girl didn't ring up the system! So, as soon as I found that out I had called the Target we purchased it from, to talk to a manager. Mind you this Target was somewhere in St Louis, and I live in TN. He was of course upset to find that no employee checked our receipts, however, he ended up giving us like 10 or 15% off the price for being honest.
So we had to buy a gift card at our local store, call it in to him and he ended up using that information and mailed us an adjusted receipt. The Target in my town would of not had that happen as they have it setup to check everyone's receipts on the way out of the store. Of course most will think, is this guy dumb? No, the PS3 has a serial number and I wasn't going to jail over a 200 dollar product.
Man, what a mess. Props for being honest, I wouldn't have been sure what to do in that situation. I mean, the store is so far away, and I wouldn't want the person who rang me up to get in trouble. But that's a $200 system, and I wouldn't feel right in the least inadvertently stealing it. You did the right thing.
Also, small world. Cookeville, TN right here.