People often list goods on Craigslist and other noticeboards just 25% below full retail price, and yet items go quick. But savvy shoppers like me can get the items brand new from a discount retailer for the same price.
I actually returned some of the kitchenware I bought at the Goodwill (second hand) store because I found the same brand new, brand-name products for the same price on sale at normal retailers, or at discount retails at the city outskirts.
In fact, there's a more upmarket competitor to Goodwill here called Buffalo Exchange (mostly selling clothing).
Mind you, in Tokyo second hand stores of all tiers and specialties were popular, all the way up to an eight-storey second-hand luxury brand department store called Komehyo in Shinjuku, Tokyo.
A Google Image Search for Komehyo captures the store quite well, actually. From last year's luxury fashion, to jewelry and more, the place was surreal to browse, and a place I insist all visitors to Tokyo visit.
Getting back to my original point, I think the reason Seattle gets away with having a second hand market that doesn't discount much comes down to the rapid growth of the city, both with Amazon, and rotation of students attending the large university. Interesting to me, nonetheless.