Hmmm....loooong list.
I regret:
-Picking up that damned FF7 official strategy guide in EB and reading it before I owned the game. It spoiled one of gaming's best moments for me (death of Aeris)
-Selling my SFC Jr., AV Famicom, CDX, Wonderswan, Saturn, R4 Limited Jogcon boxset, and tons of other stuff.
-Not buying Elemental Gearbolt last weekend for $20
-Not buying that mint white Saturn in Hong Kong for $80
-Losing the poster that went along with my VERSUS FF7 Guide
This list could go on forever....I am just a walking gaming tragedy.