Leather jacket, jeans, high tops, gloves, full face helmet, neck collar.
Kart - any adjustable front end mid 2000's or newer.
NKA or AKRA clone depending on your region, or a Predator if your track offers that.
400 piece tool kit in case from harbor freight.
$400 flatbed trailer kit from harbor freight + plywood for deck or decking boards.
Understanding partner
Empty wallet
Clean rag to wipe grin off your face.
Welcome to the addiction. I'd recommend visiting your closest track to see what classes are popular, who's got what for sale used, and perhaps someone will let you take a few practice laps.