My flat. Outside of that, computers have used up most of my money, but I've generally purchased them in parts rather than a single computer, so yeah... what else, as a single item? Hmm. Oh, wait. My ticket to the UK would probably be right up there. Can't remember how much it cost exactly, but it was certainly pricey. Same for my ticket to California. Soon, though, the engagement ring will knock any single purchase down a notch (outside of the flat).