It’s a marketing gimmick to increase interest in a property. Lets say you have a house worth 525K in a rising market. When you price it at 499 to 550, it turns up in searches up to 500 and the seller hopes the people at the lower end will stretch. It also built in cushion when the market was rapidly increasing for overbidding. Now it is used when the seller thinks their house is worth 525 to 550 but the agent things more like 500. Personally, I think it confuses the hell out of buyers.
