Spave: To save by spending, whether or not you need the item you're buying. From Word Spy:
People who spave... have an unofficial motto: The more you buy, the more you save. This sounds at first like some twisted brand of mathematics — call it Retail Math or Shopaholic Math. But the spaving secret is to purchase something — in particular, an item that you would have bought anyway — at a reduced price. For example, if you go to the mall and see an item you need that normally costs $50 on sale for $25, you'd save $25.
Problems arise when the shopper confuses the "reducing expenses" sense of "saving" with the "accumulating money" sense. The shopper would figure that, although he only needs one of them, if he were to buy two of the sale item, then he'd have "saved" a whopping $50. "Heck, I'm making money here," he says to himself. "Why not buy four of them and save $100?"