I have resold many items on ebay for a nice profit. It does take a lot of work though. If you really want to make some money, you will need to sell 10-100 items each day. Just fyi, looks for items labelled as "lot" or "lots". Resale those individually and see if you make money. I kept track of mine in a spreadsheet and was able to determine pre item profit or loss.
I now some people (women) making a nice profit by finding collectors items at yard sales for a couple bucks and reselling them on ebay for $100+ - you need to know what you are doing though and it probably needs to be your hobby/passion already.