Casio QV-4000 is from Casio's earlier digital-camera era, so it is more of a collector or experimenter buy unless the listing clearly proves the battery, storage, and transfer workflow.
Before you overpay
Check that the lens extends and retracts smoothly, flash fires, screen is readable, buttons respond, and the battery door closes firmly. Confirm AA battery setup on many kits, the charger or AA plan, and Compact Flash (Type I or II) before comparing prices. For niche or early models, confirm you can actually source the battery, card, cable, and transfer workflow.
Best use
Best for collectors, experiments, and people who enjoy unusual older digital cameras more than predictable convenience.
What to compare
Compare it with nearby Casio Exilim / QV models plus Canon, Nikon, and Sony pocket compacts. A complete battery and card setup is usually more important than a tiny spec difference.