I dunno. I don't shop for that stuff, generally. For sporting equipment, I usually go to craigslist as it's often really cheap and I like to reuse for environmental reasons, but for consumable items, it probably only makes sense to buy new. But, I've bought weights and the like from craigslist sellers.

Electronics is really my only big/expensive habit and NewEgg gets a lot of my business. I bought my last laptop directly from Dell Outlet during a sale and saved about $300 off of the same refurbished machine from Amazon. Though the ordering process from Dell was stupidly inconvenient as I had to get an agent involved to apply the discount and to deal with payment, as for some reason my business debit card wouldn't work. It took half a day, so it's not something I would do for less than a significant discount.

And, as I mentioned, Walmart is often a better choice for regular stuff, and they now have a quite large online selection including stuff that is not stocked in stores.

Oh, yeah, I buy truck stuff, parts and the like for my old pickup. I buy about half from Amazon market sellers and half direct from diesel specialty dealers. And parts for my old RV, same story. Big items never come from Amazon, though; my rooftop AC replacement was purchased from a local dealer for $240 less than the Amazon price.

I guess Google Shopping is how I've found most of the specialty shops.