Passing up on the Alternators two-packs when TRU put them on clearance. Not buying Leader Megs when I could've. Ditto for Robo-Vision Prime. Passing up on Alternators Tracks and Meister when they were re-released. No, they'll be clearanced 'cause everybody already has them. Gold MP Convoy at BotCon. Not buying more of the Korean BW II/BW Neo reissue stuff when I could've.
Probably anything G1 when I was in my Cybertron phase... don't remember anything specific, but they all got away. Probably Alt. Mirage. I bought Prime instead. Buying only 1 Alt. Camshaft and 1 Alt. Miester on clearance