Bulk buying and selling on eBay
To find items for sale in large quantities, search for terms like "bulk," "job lot," or "wholesale." You can research how much they usually sell for as single items to see whether they're a worthwhile investment. You can also check out what's currently trending on eBay.
If you're buying items to resell on eBay, you should register as a business seller.
Buying and selling seasonal items
Another opportunity is to look for out-of-season goods. If you're willing to hold on to items for a while, stocking up on things such as summer clothes during winter, or Christmas gifts once the festive season has passed, could be very profitable.