Things I've done on eBay mostly successfully ---
1) Go to garage sales, rummage sales, dollar stores --- and, buy stuff at the discounted price.
2) Place on eBay with a minimum sale price, and let the bidding begin
For a year's effort, I've made as low as $500 ... but, I've also had a year of > $10,000
I know people that make an entire living this way. It just works. I don't understand it either, but people like buying junk you wouldn't otherwise give your mother-in-law.