Just in your notes app or whatever. It scratches the same itch as making the purchase. And then you have the whole list there to consult when you have extra money to buy something fun - but the cool thing is if you let the list sit there for a whole you usually dont even want the thing anymore. And then if time passes and you still want it it feels more worth it! Honestly get it out of your mind and on a note and it interrupts the shopping cycle.
