Just go knock on the door and say you were wondering about the old car in the barn. If you're real young, it will probably help. You'll know the mood right away. If they pull out a gun, just apologize and leave immediately. Otherwise, strike up a conversation about the car if they are happy to talk about it. Don't jump immediately on "I want to buy it", just ask about it. Get the story if there is one, find out if they know what it is (you can research later to know if they're full of crap or not) and don't act creepy about it. It's pretty simple, play it by ear from there. Either they'll offer to sell it to you, or after you've chatted for awhile, you can ask. Then either way, do your research based on the VIN #'s and anything else you can write down from the car to see what it's really worth.