It can be interesting to just browse through YouTube to see what you can find. My latest is a channel by a guy who buys "Liquidation Pallets" from Amazon. Basically it is boxes of stuff that Amazon customers have returned, or overstock stuff, etc. Anyway, the pallets (4 or 5 big boxes) may have a total MSRP of about $1000 or more, if the items are new. Which most are not. Then the guy goes to liquidation sites, and bids on them. So, he can get a pallet of $1500 worth of stuff for, say $150. This guy has a resale shop, plus sells stuff on eBay, FB marketplace etc. So, if stuff is unopened, or in unbroken condition, he can resell the stuff and hopefully get his money back, plus profit.

If I were younger, and did the flea market circuit, I would do something like this. In one video, he found a like new watch with a new price of about $500. He figured he could re-sell it for about $200 or $300, which was already more than he paid for the pallet.