It said the rest went toward production of the xkcd book. I don't know if that means solely inventory and production costs, or if it includes administrative overhead as well (I would assume some)
Costs were for inventory & production (we don't have any employee salaries):
Book production (cost of printing, binding, shipping to xkcd fulfillment center) - by far the most expensive thing
Contracted design work
ISBN registration
A few FEDEX shipments for prototypes
[Ultimately, we agreed with xkcd to share the costs and deduct those from the total revenue before splitting the profits, but I needed to put a hefty downpayment and it helped to have the $ in the bank.]
Book production (cost of printing, binding, shipping to xkcd fulfillment center) - by far the most expensive thing Contracted design work ISBN registration A few FEDEX shipments for prototypes
[Ultimately, we agreed with xkcd to share the costs and deduct those from the total revenue before splitting the profits, but I needed to put a hefty downpayment and it helped to have the $ in the bank.]