That old adage has many exceptions to the rule, BTW. My latest horse cost me not one penny to buy, but he's by far the nicest animal I've owned in the last 20 years.
I didn't say the places I shopped weren't expensive normally but they do have kicker sales sometimes, which is when I buy. If you don't need something right away you can wait and get a good deal.
I bought myself a pair of fullseat breeks on sale. I'd been lusting after a pair for several years, but couldn't justify the price. Caught them on sale, and got them for less than what I normally pay for regular breeks.
I might shop at Goodwill for my regular outwear, but there's no way I'd buy used breeks. Don't know why. It just seems oogy to me.
Plus, ebay isn't what it used to be. Now many sellers are just on-line merchandisers with new stuff, and the same guarantees you can find anywhere else on-line. I'd rather buy from Amazon than ebay any day.