If you are looking for an item that is very specific or hard to find, there is an application on eBay that lets you follow the search and sends you an email each time a seller lists your desired item. You just need to type a product name into ebay's search bar and click 'follow this search'. Be as specific as possible for the most accurate results, then when someone lists the item you will receive an email. This way you will not need to spend hours trawling through the site.