They know that if you focus on what you're spending, you may have second thoughts. But remember that every dollar you spend is a dollar you're not saving. That's the only real way to obey such a sign. There, I'm done venting. Let's move on.
Retailers like to create a sense of urgency.
They know that the moment you walk out of the store or click out of their Web site, they lose their best chance of making a sale. True enough, but for all you know they'll extend the sale, or honor the sales price even when it's over. Or maybe they have a truckload of the stuff parked out back, or can order more from the manufacturer or another store. The sellers may be experts, but you can be a formidable amateur opponent. Now go play this game to win.