I grant myself a stipend of $100/month of Geek Money, which I use to feed my anime/manga habit or buy Magic cards, or rarely other miscellaneous stuff like adding a new weapon to my collection of medieval arms, but I haven't had a new acquisition there in half a year, and I only buy manga or anime when I find something a really must have - still waiting for the next issue of Welcome to the NHK and of course Excel Saga Vol. 16, but I have also been plugging holes in my Blade of the Immortal collection when the fancy strikes me. Most of the time I rent until I find something I want to buy, so each month I might not spend all $100, or even 50, but 50+ is about right.