I've never heard of Bonanza, but Etsy is pretty different: it caters to people who handcraft stuff and sell it directly to customers. You can do that on Ebay, but Ebay is(/was) really more of a giant garage sale.
Amazon used to have a facility where any regular Joe could resell some used item on there: you'd see the new item listing, and then you'd see "available for as low as $$$ from these new and used sellers" that you could click on. You can still buy from other sellers there, but only if they have paid sellers' accounts, which keeps out the regular Joe who just wants to sell a few things a year, like the time when I resold a used table saw I didn't need any more.
