Probably the dumbest thing I have is a recent ebay purchase. For 10 bucks, I got the whole driver's side half of the fiberglass nose piece off of one of Johnny Benson's Toyota Certified Used Vehicles trucks. It's a race used piece and still has all of the grime on it even.
Here's a shot of the truck piece:
my most valuable car is 1:64 scale jimmie johnson 2004 spongebob squarepants car