Mystery Mansion #75904 worth

Based on the information provided, the catalog shows that the Mystery Mansion #75904 — LEGO Scooby Doo Set Value has a typical used value of $300. Since the second item, LEGO Mystery Mansion (75904-1) (Scooby-Doo), is listed as unpriced in your screen view, I cannot provide a specific valuation for it. For the first item, the $300 used value reflects what these sets typically sell for when used; you can check the live eBay listings shown on your screen to compare current asking prices against this sold-value data.