OK - eBay does NOT count, as it's technically not "the wild".
I'm talking game stores, thrift stores, garage sales, friends, whatever else...
Here's mine (although they have all been sold - sniff, sniff):
1. NES console test cartridge (perfect label) $3.00
2. MINT, complete Q*Bert's Qubes for 2600 (so choice) $2.99
3. StarFox Super Weekend Competition cart for SNES (really good condition) $9.99
Try to limit them to three, unless you just have a couple of more amazing finds that warrant a story.