It lets you change your costumes quickly and store them.
Also, let's say you find a cool shield or sword somewhere and want to save it... you can set the sword/shield to your character, then save the slot so that you have the code later on... its pretty handy. 7.5 k makes it something you should get AFTER the customize pack, the house, the horse, lantern, etc... but not totally outrageous (look at the 50,000 piano for example).