Study what sells on eBay and make a list of items to look for. Shopping at estate sales will allow you to mark up your auction prices significantly if you know what you are looking for. I have seen friends of mine make $25,
Kung Fu Panda Season 1 DVD Box Set,000 on a table that no one wanted,
Nikita Seasons 1-4 DVD Box Set, of course it was from the 18th century,
Longmire Season 2 DVD Box Set, but you never know..