If you're going to distribute buttons, you'll need a box to ship them in. Include the book and its starting to sound like a boxed set... ;)
Of course, it would be a pretty empty boxed set. Cool ways to flesh it out might include:
A GM screen with principles, agenda, GM moves, dungeon moves, etc
An anthology of starters/adventures/maps/etc., perhaps crowd-sourced from the Adventurers Guild
1 pair custom dice for each class with that classes symbol (an upgrade from the pins)
Laminated move/special move reference sheets
(If you went the kickstarter route you could probably build those things as different reward levels so that backers could decide how much bling they wanted in their boxed sets) (A later expansion could have new classes with pin/dice and more starters/adventures/maps/etc.)
Ok, enough day dreaming...