Either the time I found 4 N64 games from goodwill for 3 bucks each (Mario Kart 64, Mario Party 2, Yoshi's Story, Wipeout 64),
Or a few weeks ago when picking up a big lot of PS1/2 games they must have just put out and Champions: Return to Arms (PS2) was there CIB, totally worth the $3 they were charging!
Honorable mentions are the Sega Saturn games I found CIB at the flea market, the PS1 RPG lot from the flea market (Suikoden, FF9, FFT), or the NIB Super Slim PS3 from the flea market.
I had a decent year...