Call the listing agent on the sign and they can tell what the asking price was and if it sold fast or how long on the market. If it sold fast, probably close to asking price! If not you need to wait until it closes and no need to wait 30 days, it because public record the day ot closes, call the listing agent back. As mentioned, a bit of a moot point. Unless you are a neighbor thinking of selling I dont understand the basis for the question. Call me if you care to discuss.
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Best of luck!