I carry nothing! I say poof and the deck appears! MUHAHAHA
fine...
I usually carry only 1 deck with me.
But if I know that I will be performing, I carry 1 deck of any kind and my small packet of gimmicks and extras. These include most of daryl's printed cards, split-decision, cards for angle zero, double backs, face, blanks, etc. A small packet of these can easily last me 30 routines.