As a player, I bring somewhere around 15-20. Generally 2 of each a few more d6s, and a few others depending on what weapons/spells/powers I expect to be using.
As a DM I have three 'super-sets' that each consist of 3d4, 5d6, 2d8, 3d10, 1s12, 1d20. I keep two sets on my DM table and the third...