I appreciate the detailed brief, but I need to flag a mismatch: your search results are about U.S. real estate markets (home prices, median listing prices around USD $400K+), not used audio equipment pricing. They don't contain comparable data for Bluetooth headphones or any audio gear.
Without access to actual used Dual Bluetooth 5.1 headphone comps or typical market pricing for this specific model, I can't confidently anchor a verdict on whether USD $160 is a bargain, fair, or ambitious. The model designation "Dual Bluetooth 5.1 (Headphones)" is also too generic—Dual is primarily known for turntables, not headphones, so either the brand name is unclear or this is a lesser-known model I'd need to verify.
Here's what I'd need to write this properly: the exact Dual model number, current condition details (mint/good/fair/parts), and access to recent sold comps from audio marketplaces (eBay, reverb, Craigslist, etc.) rather than real estate data. If you can supply the model name or number and any comps you've seen, I'll write the tight two-paragraph take you're after.
Independent perspective — not a price guarantee. Always verify condition, accessories and provenance before purchase.