My wife scours local auctions for EBay stuff....sold an old vase for $275 last year, vase came in a box with something else that we wanted for ourselves. Old sets of china sell really well by the piece.
She does pretty well, has an EBay Store now. She refuses to tell me how much is in her Pay Pal account. She's selling-off her Mom's huge collection of antique oil lamps and hand made quilts. She still turns out a quilt a month at 83 yrs of age!
Buyers pay actual shipping...she might charge something extra if the item requires a lot of packing, like an oil lamp or dishes.
BTW, we declare profits at the end of the yr on our 1040 since we have an S-corp for our trucking biz. You can scoff at that or do as you wish, but I'm pretty heavily oriented toward maintaining my freedom and assets. The IRS has all of the cards in the deck stacked in their favor, I have no interest in taking a seat across the table from them. YMMV.