I've sold things on ebay as secondary income. It was basically an online Garage Sale. A family member's store went belly up and I was left with stock in my storage space. It did VERY well.
The key is to find other similar items on ebay and Amazon to price competitively and get the proper copyright that gets people's attention. Be sure to weigh the product for proper s/h fees.
I know there are wholesale companies where you can buy brand new items in bulk and resell at markup. Some companies will even drop ship directly on your behalf.
I would caution people to first find a company in the US if possible
. China as a secondary recourse. Have product sent to you first to see what your customers are getting. Potential MAJOR profits.
For people just starting out, I would even suggest going to the $1 store and finding name brand items and resell at markup. You'd be surprised at what people buy. Keep your receipts.